Today? A look at the best pass defenses at preventing first downs. This time, I am also going to era adjust these ratings. In 1969, the Vikings faced 459 pass plays (410 pass attempts, 49 sacks) but allowed only 88 passing first downs. That’s a remarkable rate of just 19.2%, the best since World War II. It’s also the best rate on an era-adjusted basis. The league average in the NFL in 1969 was 29.0%, which means this iteration of the Purple People Eaters was 9.8% better than league average, the highest differential ever. [click to continue…]
When it comes to the AP Defensive Rookie of the Year award, one thing is clear: being a high draft pick really, really helps. On average, the last 15 players were drafted with the 11th overall pick, and all but one was a top-18 pick! This award is extremely skewed in favor of early draft picks. Take a look:
Today’s guest post/contest comes from Thomas McDermott, a licensed land surveyor in the State of California, a music theory instructor at Loyola Marymount University, and an NFL history enthusiast. As always, we thank him for his hard work. You can view all of his work at Football Perspective here.
If you can get five people in a room to agree on what a sports dynasty is, you’ll probably have achieved the most miraculous agreement in history since the Congress of Vienna. We know a sports dynasty when we see one (the current Patriots, the New York Yankees, 1990s Bulls, etc.), but it becomes less clear once we attempt to actually define it:,When does the dynasty start? How long must it last? What are the requirements?
In this article on NFL dynasties, FiveThirtyEight does a nice job of negotiating the quagmire by just listing the “best team over any number of years”.1 I’m going to do the same thing here, but focusing solely on NFL defenses since the merger (regular season only). The metric is points allowed by the defense (meaning: fumble, interception, kick and punt return touchdowns, and safeties aren’t included), adjusted for era and strength of schedule (basically, SRS ratings). Regular readers may recall that I published these results back in August 2015. To differentiate this stat from Pro-Football-Reference’s DSRS, I’ll call it “DfSRS”.
Below is a table of defensive dynasties, ranging from 1 to 15 years: [click to continue…]
- Their definition of “best” being their ELO ratings. [↩]
In general, sack data for team defenses is not super consistent from year to year. Since 1990, the correlation coefficient between sack rate (for defenses) in Year N and sack rate in Year N+1 is 0.27. The best-fit formula (using a linear regression cover the years from ’90 to ’16) to predict sack rate for next year would be to use a constant of 4.8%, and then add 26% of the defense’s sack rate from the prior season.
That’s not too surprising of a result, but I was curious whether adding each team’s concentration index would help make sacks more predictive. As it turns out, the answer is a little complicated. I ran the same regression as above, but used each defense’s concentration index as a second variable. The change didn’t improve the correlation at all, and the p-value on the concentration index variable is 0.65, making it essentially meaningless. But it may be a little more complicated than that.
The team with the biggest decline since 1990 in sack rate, year over year, is the 2008 Chiefs. In ’07, Kansas City had a sack rate of 7%, the 8th-highest in the NFL. In 2008, it dropped to just 2%, the lowest in modern NFL history. And in 2007, Kansas City had the second most concentrated pass rush in the NFL, largely based on Jared Allen and his 15.5 sacks. In ’08, Allen was in Minnesota, and the Chiefs didn’t have a single player more than three sacks. This makes perfect sense: KC’s pass rush was very good in ’07 but centered around a superstar defender; without him the next year, the pass rush fell apart.
Sounds simple, right? Except that’s just one example. In 2000, the Titans had the 2nd best pass rush but just the 28th most concentrated: six Tennessee defenders had at least four sacks, and another six had at least two sacks, while Jevon Kearse and his 11.5 sacks made up just 21% of the team’s sacks. This sounds like a diverse pass rush that should be more sustainable from year to year, but in ’01, the team’s sack rate basically fell in half.
Analyzing sack data is very complicated: you have to factor in regression to the mean, Game Scripts, and also the randomness involved with something that only happens once every 15 or so passing plays. That said, the table below shows the 50 teams with the most concentrated pass rushes since 1982. In other words, these were the teams that were built around just one or a handful of elite pass rushers: [click to continue…]
Today, we will do the same thing but by position, using AV as our tool of measurement.
First, let’s start with defensive linemen. On average, from 1970 to 2016, 50% of all AV came from players 27.0 years of age or younger as of September 1st of the season in question. That number rose to as high as 27.6 in 1999, dropped to just 26.1 in 2013, and has been around 26.5 over the last three seasons.
Good instagram post by Tony Khan yesterday: Since 2001, there have been more interceptions made by defensive players aged 26 than by players of any other age.
That was true for this past season, too, where 70 of the interceptions came from players that were 26 years old in 2016. Perhaps more interesting: the median age for interceptions, by defenders, was 26 years. What do I mean by that?
Well, 2% of all interceptions in 2016 came from players 21 years of younger; 7% came from players 22 or younger, 14% from 23 years or younger, 28% from 24 or younger, 39% from age 25 or younger, and 56% from age 26 or younger. So if you sort all interceptions by the (ascending) age of the defender, you need to go up to age 26 to cross the 50% mark.
I looked at the September 1st age of every player who recorded an interception in each year from 1940 to 2015 (I haven’t updated by database for 2016 just yet). The graph below charts the median 9/1 age in each season (i.e., what is the youngest 9/1 age you need to use to make sure you capture at least 50% of all interceptions from player that age and younger): [click to continue…]
Take a look at the Broncos pass defense this year, compared to the Broncos pass defense last year:
Three years ago, I looked at the Seattle pass defense and calculate how many standard deviations above average the Seahawks were. At the time, I compared them to an average of the other 31 defenses rather than an average of all 32 defenses, including themselves. I don’t know if there’s a right or wrong answer there, but I’m going to use the latter methodology today, which will explain why the numbers are slightly different.
Anyway, Seattle was 2.80 standard deviations above average in ANY/A allowed in 2013. That’s because Seattle’s pass defense allowed 3.19 ANY/A, while the league average was 5.89 ANY/A. That’s a difference of 2.70 ANY/A, and the standard deviation among the 32 pass defenses that year was 0.97. Divide 2.70 by 0.97, and you see that Seattle was 2.80 standard deviations above average.
The 2016 Broncos? They are allowing just 4.25 ANY/A. That is over a full yard “worse” than Seattle, but worse needs to be put in quotes. For starters, the league average is 6.25 ANY/A this year; in addition, the rest of the league is bunched together. The standard deviation for the 32 pass defenses is 0.74 ANY/A. That means the Broncos have a Z-Score of 2.69 standard deviations better than average (here, negative is better).
That puts Denver as the 5th best pass defense, by this metric, since 1970: [click to continue…]
In 2013, the Bears allowed 100-yard rushers in six straight games: those players were Eddie Lacy, Reggie Bush, Ray Rice, Benny Cunningham, Adrian Peterson, and DeMarco Murray. Chicago was the 5th team since 1960 to allow such a streak.
In 2006, the Rams had their own six-game stretch of allowing opposing running backs to hit the century mark: those backs were LaDainian Tomlinson, Larry Johnson, Maurice Morris, DeAngelo Williams, Frank Gore, and Edgerrin James.
In 1998, the Bengals allowed an opposing runner to hit the 100-yard mark in six straight games: Priest Holmes, Kordell Stewart, Eddie George, Napoleon Kaufman, Terrell Davis, and Fred Taylor were the stars there.
The first time, since at least 1960, that a team allowed a player to rush for at least 100 yards in six straight games came in 1979, against the Raiders. Oakland only allowed six 100-yard rushers all season, but it happened in consecutive weeks by Paul Hofer, Earl Campbell, the 7th best player named Mike Williams in NFL history, Rob Lytle, Chuck Muncie, and Mike Pruitt.
But now, for the first time in NFL history, the San Francisco 49ers have allowed a 100-yard rusher in seven straight games. Fozzy Whittaker went 16-100 in week 2, Christine Michael had 20-106 in week 3, Ezekiel Elliott had 23-138 the next week, David Johnson went off for 27-157 in week 5, LeSean McCoy ran roughshod 19-140-3 the following week, and Jacquizz Rodgers had 26-154 last week.
Today? Mark Ingram had 15 carries for 158 yards. Up next week? A rematch against David Johnson and the Cards.
The Jets defense was pretty good last year. New York allowed 29 touchdowns in 2015, tied with the Broncos for the fourth fewest in the NFL. But the Jets allowed a ton of long touchdowns: on average, those 29 touchdowns scored by opposing offenses came from 23 yards away.
That may not mean much to you in the abstract, but only three other defenses (Ravens, Vikings, Rams) saw allowed touchdowns from, on average, at least 20 yards away; by contract, the other 31 teams allowed touchdowns that gained, on average, 16.22 yards. One reason I initially thought the Jets defense fared poorly in this statistic is because of the team’s historically great run defense, and that’s partially true. The Jets allowed only four rushing touchdowns last year, and they came from 1, 1, 2, and 18 yards away.
But if you look at only passing touchdowns, the Jets defense still allowed the longest average touchdown at 26 yards (even worse than the Saints!), compared to an NFL average of 19 yards. The Jets allowed 15 touchdown passes of 20+ yards last year, tied with New York’s other team for the most in the NFL.
What was the reason for those long touchdowns? I went back and re-watched all 15 touchdowns, and tried to assign blame. In most cases, it was pretty easy. [click to continue…]
On December 12, 1965, the Eagles traveled to Pittsburgh and won, 47-13. That game was not necessarily all that notable: entering the game, the Steelers were 2-10 and the Eagles were 4-8. But that day, Philadelphia produced one of the greatest defensive efforts in NFL history. The Eagles defense had three pick sixes, recorded five sacks, forced five fumbles (recovering three), and — most remarkably — had nine interceptions. If a 12-turnover, 3-touchdown day sounds really good to you, that’s because it is.
The past two days, we have looked at the Ryan Index, my measure of defensive aggressiveness/effectiveness. The best game last year came by the Cardinals defense in week 16 against the Packers. Arizona allowed just 8 points (+8), recorded an interception (+4), forced five fumbles (+15), recovered three (+3), had 9 sacks (+18), and scored two defensive touchdowns (+12). That’s a total of 60 points, the most by any defense since those same Cardinals were blanked by the Seahawks, 58-0, back in 2012. [click to continue…]
The football community is in mourning this week, after the passing of Buddy Ryan. Remembered as one of the most celebrated and color defensive coaches in history, Ryan’s most famous accomplishment was guiding the ’85 Bears to a Super Bowl — on the backs of one of the greatest defenses in NFL history. But Ryan’s defenses weren’t just known for being great: they were known for being great at attacking the opposition. Some defenses, like the 2009 Jets, were great defenses but were not all that aggressive: those Jets ranked 1st in points, yards, first downs, and yards per attempt, but were 11th in interception rate and below-average in sack rate.
Ryan’s defenses were known for their big plays — sacks, fumbles, interceptions, and scoring plays. So I decided to create a formula using some gut and fuzzy math to create a Ryan Index of aggressiveness. Here’s the formula: [click to continue…]
How do the Broncos stack up with the best playoff defenses?
The Broncos just capped off a run that saw the defense carry Peyton Manning and a below-average offense to a Super Bowl title. Denver held the highest scoring team in the league to just 10 points in the Super Bowl. As a result, debate ensued as to where the Broncos ranked among other great Super Bowl winning defenses. And just last week, Chase looked at the net points allowed by each Super Bowl champion. [click to continue…]
A quick checkdown today, looking at the net points allowed in the playoffs by each of the 50 teams that won the Super Bowl. What do I mean by net points? It’s pretty simple:
(Touchdowns allowed to opposing offenses) * 7 + (Field Goals allowed) * 3 – (Touchdowns scored by the defense) * 7 – (Safeties scored by the defense) * 2
I have decided to ignore special teams touchdowns — both for and against that team — as this is just a look at defenses. And obviously this is a very basic look: it doesn’t incorporate number of drives faced, average starting field position, missed field goal attempts, or quality of opposing offense (or era). But hey, I said it was a quick checkdown!
Here’s how to read the table below. Let’s use the 1985 Bears as an example. You may know that Chicago shut out both NFC opponents en route to the Super Bowl, where the Bears allowed 10 points. But that’s a bit misleading, because Chicago’s defense was better than that. The 1985 Bears played in three playoff games, and the defense scored two touchdowns and recorded a safety (total of 16 points). The defense did allow 10 points, via a touchdown and a field goal, but that means the Bears defense allowed -6 net points in the playoffs, or -2 NP/G. [click to continue…]
New Orleans has allowed 4,217 passing yards this year (which includes yards lost by the opposing team on sacks) on 538 dropbacks, which is already pretty bad. That translates to a 7.84 Net Yards per Attempt allowed average, which is the worst in the NFL by half a yard per attempt. But where things get really bad is in touchdowns and interceptions. New Orleans has allowed an unbelievable 43 passing touchdowns through 15 games, the most in NFL history. In addition, the Saints have intercepted just 8 passes, tied for third fewest in the league this year.
That translates to an 8.77 Adjusted Net Yards per Attempt average, after giving 20 yards for each touchdown pass and subtracting 45 yards for each interception. That is, by a decent measure, the worst rate in NFL history. The current record belongs to the 0-16 Detroit Lions, who allowed 8.53 ANY/A. Only three other teams — the ’81 Colts, the ’69 Saints, and the ’63 Broncos — have even allowed 8.00 ANY/A over a full season. [click to continue…]
A couple of weeks ago, I looked at the Adjusted Yards per Carry data for 2014 offenses; today, the same information but for the other side of the ball. As a reminder, here’s the formula for calculating Adjusted Yards per Carry:
Adjusted Rushing Yards per Carry = (Rush Yards + 11 * Rush TDs + 9 * Rush First Downs – Kneel Yards Lost ) / (Rushes – Kneels)
Let’s use the Detroit Lions defense as an example. The Lions faced 350 rush attempts last year and allowed 1,109 rushing yards and eight touchdowns. However, seven of those rushing attempts were actually kneels by the opponent (for -7 “rushing yards”), so we need to back those out of the data. The Lions also allowed 59 rushing first downs, or a first down on 17.2% of all carries. As a result, Detroit allowed 5.06 Adjusted Rushing Yards per Carry last year, the best rate in the NFL. The league average last year was 6.63, which means the Lions were over a yard and a half above average per carry. Multiply that difference by the 343 non-kneel runs that Detroit faced, and the Lions rush defense was 541 Adjusted Rushing Yards above average (here, negative is better), the top value-producing rush defense in the NFL in 2014. [click to continue…]
Yesterday, I looked at the best defenses in football history in terms of (estimated) points allowed on an (estimated) per drive basis. Today, the reverse: the worst defenses in history, at least, without adjusting for era, in terms of points allowed per drive.
The 1981 Colts take the top spot, and that’s not going to be a surprise to any fan of NFL history. Those Colts teams were terrible, particularly on defense. In ’81, Baltimore beat New England 29-28 in week 1, beat New England 23-21 in the last game of the season, and lost every game in between. In ’82, Baltimore finished 0-8-1. In fact, beginning in December 1980, over the team’s next 31 games, the Colts went 3-1 against the Patriots and 0-26-1 against the rest of the NFL! And beginning in ’81, the Colts went 24 straight games without being favored.
The ’81 Colts finished last in just about every defensive category, including points, yards, turnovers, first downs, passing touchdowns, rushing touchdowns, and net yards per attempt. Baltimore’s defense ranked in the bottom three in both rushing yards and passing yards, too. Baltimore allowed 533 points, which remains the most in a single season in NFL history, undisturbed by the modern era. [click to continue…]
In 2014, there were 17,879 pass attempts in the NFL, and another 1,212 dropbacks that ended up as quarterback sacks. Therefore, the 2014 NFL sack rate was 6.35%, as quarterbacks were sacked 1,212 times on 19,091 dropbacks.
The Buffalo Bills defense was fantastic in general last year, and even moreso with regards to sacks. Buffalo faced 613 opponent dropbacks last season; given the league average, we would “expect” the Bills to have recorded 38.9 sacks.1 In reality, Buffalo sacked opposing quarterbacks 54 times, or 15.1 more than “expected” last season. Only one other team, the Giants at +10.9, reached double digits in sacks over expectation.
The worst team, by a good measure, was Cincinnati. The Bengals faced 628 opponent dropbacks but recorded only 20 sacks! Using the league average as our guide, we would have expected Cincinnati to take down opposing passers about 39.9 times, which means the Bengals fell 19.9 sacks shy of expectation. Only Atlanta at -15.3 and Oakland at -13.6 were within shouting distance of the Bengals when it came to anemic pass rushing. [click to continue…]
- This is simply the product of 613 and 6.35%. [↩]
Quite the clickbait title, I know. But given where this post is going, I thought precision was more important than anything else.
Over the last three seasons, Seattle has allowed 15.2 points per game. That’s really, really good. How good?
There are flaws with using points allowed as a measure of defensive play, of course. Seattle is known for its long drives on offense, which limits the number of possessions an opponent might have. And the Seahawks offense generally puts the team’s defense in pretty good situations. Using points allowed per drive might be preferable, or using DVOA, or EPA per drive, or a host of other metrics. And adjusting these results for strength of schedule (or, at least, removing non-offensive scores) would make sense, too.
But hey, it’s Friday, and I wanted to keep things relatively simple.1 Points allowed is a number we can all understand. Given our era of inflating offenses, it’s quite possible that Seattle’s 15.2 points per game average doesn’t stand out as particularly impressive to you. After all, the ’76 Steelers once allowed 28 points over a nine-game stretch! But consider that since 2012, the NFL average has been 22.6 points per game, which means the Seahawks have allowed 7.4 fewer points per game than the average defense.
How good is that? [click to continue…]
- In about ten minutes, we can all have a good laugh at this line. [↩]
Ten years ago, the teams with three of the four best defenses in football missed the playoffs. The Buffalo Bills ranked 1st in Adjusted Net Yards per Attempt allowed and 2nd in Adjusted Yards per Carry allowed. That year, Sam Adams, Takeo Spikes, Terrence McGee, and Nate Clements made the Pro Bowl, while Aaron Schobel had 8 sacks and London Fletcher was London Fletcher but younger. The team ranked 1st in DVOA by a good margin, but finished 9-7, narrowly missing the playoffs.
That year, Baltimore ranked 4th in ANY/A allowed, 3rd in AYPC allowed, and 2nd in DVOA. The Ravens weren’t quite as good on defense as the ’00 or ’06 iterations, but still had Terrell Suggs, Ray Lewis, Adalius Thomas, Chris McAlister, and Ed Reed (not to mention a 37-year-old Deion Sanders). Of course, this was the Ravens team that was one of the most one-sided team in NFL history. Baltimore also finished 9-7 in a year where six AFC teams won double-digit games.
Over in the NFC, Washington’s defense ranked 1st in Adjusted YPC and 3rd in ANY/A in Joe Gibbs’ first season back in D.C. Marcus Washington was the team’s only Pro Bowler, but the defense featured a rookie Sean Taylor, Ryan Clark, Shawn Springs, Antonio Pierce, and Cornelius Griffin. Despite ranking 4th in defensive DVOA, the team won just six games.
So why today are we looking at these three teams, nearly ten years later? It’s not to remind you that Drew Bledsoe, Kyle Boller, and Mark Brunell failed to guide those teams to the playoffs. As it turns out, these are the last three teams to finish in the top five in both ANY/A allowed and AYPC allowed and still miss the playoffs. In fact, since 1970, just nine other teams have managed to pull off that feat.
- In 2002, Miami ranked 5th in both ANY/A and AYPC allowed, while the Panthers ranked 4th in both categories. Carolina was a year away from a Super Bowl appearance, while the Dolphins were nearing the end of their Jason Taylor–Zach Thomas–Sam Madison run.
- In 1999, a year before The Year, the Ravens ranked 2nd in both metrics but finished just 8-8.
- In 1998, the Raiders and Chargers had great defenses, but neither could challenge (or slow down) the Broncos. Behind Norman Hand, John Parrella, Kurt Gouveia, Junior Seau, and Rodney Harrison, the Chargers fielded one of the greatest rush defenses of all time; unfortunately, they also fielded Ryan Leaf and Craig Whelihan at quarterback. The Raiders had a pair of blue chip 22-year-olds in Darrell Russell and Charles Woodson, but first-year head coach Jon Gruden couldn’t get the offense to the playoffs.
- You know all about the 1991 Eagles, so of course they are on this list.
- The 1987 Giants, a year after winning the Super Bowl, still produced a Super Bowl caliber defense behind Lawrence Taylor, Carl Banks, Pepper Johnson, and Harry Carson, but the team’s offensive line (3rd most sacks allowed, 2nd worst YPC average) torpedoed the offense.
- In 1978, a year before nearly carrying the team to the Super Bowl, Lee Roy Selmon and Dave Pear helped Tampa Bay rank 1st in AYPC allowed and 3rd in ANY/A allowed. But a miserable offense led to a losing record in the franchise’s third season.
- The 1974 Packers ranked 5th in both categories. The defense sent Ted Hendricks, Willie Buchanon, and Ken Ellis to the Pro Bowl, but if you think this is just a thinly-veiled reason to bring up John Hadl, you are a regular reader of this blog.
Since 2004, six teams have ranked 1st or 2nd in AYPC allowed but missed the playoffs. Two of those seasons occurred last year, with the Jets and Cardinals, respectively. The 2006 and 2007 Vikings also join that list, along with the 2007 Ravens (a year after a magnificent season) and the 2010 49ers (a year before a magnificent season).
Having a dominant pass defense is even more likely to send a team to the playoffs. Since 2004, only one team — the 2012 Bears — ranked 1st in ANY/A allowed but missed the playoffs. The 2009 Bills are the only team to rank 2nd in ANY/A allowed and miss the playoffs, while the 2013 Bills, 2010 Chargers, and ’05 Jets are the only teams since ’04 to rank 3rd in ANY/A allowed and still fail to make it to January.
Too Long; Didn’t Read
- The 2004 season was kind of crazy.
- Since 2002, 24 teams have ranked in the top five in both pass defense and rush defense; five of those teams missed the playoffs, although the last 16 teams pull off this feat have made the postseason.
- Of the 36 teams to rank in the top 3 in Adjusted Yards per Carry allowed since 2002, only 19 of those teams made the playoffs. Although it’s worth noting that eight of the 17 teams to miss the playoffs out of this group ranked 20th or worse in ANY/A allowed.
- 28 of the 36 teams to rank in the top 3 in ANY/A allowed made the playoffs.
A few years ago, Mike Tanier wrote a great column on the 1986 Eagles, the team that obliterated the record for sacks allowed with 104. But since Philadelphia had 53 sacks of their own (having Reggie White tends to help), Philadelphia was able to pull into a tie for worst sack differential of all time. That honor of -51 is shared with the 1961 Minnesota Vikings, an expansion team led by our good pal Fran Tarkenton. Minnesota’s defense recorded an absurdly low 16 sacks that season (the 14-team league average, including Minnesota, was 38), and led the league by a substantial margin with 67 sacks, most of them attributed to Tarkenton. Back then, expansion teams were not very good, although the team would turn things around soon.
What about the teams with the best sack differential? Four teams have recorded 40 or more sacks than they’ve allowed. [click to continue…]
The Fearsome Foursome Rams of Merlin Olsen and Deacon Jones fame went 51 straight weeks without allowing a 100-yard rusher. In the final week of the 1964 season, Jim Taylor rushed 17 times for 165 yards against the Rams (he also picked up 56 receiving yards). Over the next three years, no opponent rushed for over 100 yards against Los Angeles. That held true for the first nine weeks of the 1968 season, too, until San Francisco’s Ken Willard broke that mark with a 128-yard performance. That was the only time from 1965 through 1968 that the Rams allowed a 100-yard rusher. Incredibly, there was a stretch of 93 games where the Rams allowed a 100-yard back just five times… and three of them came at the feet of Jim Taylor!1
In 1989, Gerald Riggs, then with Washington, rushed for an incredible 221 yards yards in week two against Philadelphia. That was noteworthy, because for the next 53 games, no opponent rushed for 100 yards against Reggie White, Jerome Brown, and the Philadelphia Eagles defense. We know how dominant the 1991 defense was, but the rush defense was pretty stringy in the surrounding years, too. It wasn’t until Emmitt Smith broke through with a 30-carry, 163-yard day in November 1992 that the streak was snapped. [click to continue…]
- In addition to Willard, Baltimore’s Tom Matte also accomplished that feat. And Matte did put up a 99-yard performance in 1965 against LA, too. By 1969, the Rams were positively pedestrian against the run by their standards, allowing both Gale Sayers and Tom Woodeshick to hit the 100-yard mark. Then nobody did it again for 27 games. [↩]
But today, I want to look at which defenses were the best in regular season history, and see where Seattle stacks up. Bill Barnwell had an interesting post during Super Bowl week. He used the statistical measurement known as the Z-Score to show that Seattle was the tenth best defensive scoring team in NFL history. Don’t be too confused by the idea of a Z-score: in English, this just means that Seattle’s defense — and yes, I am going to conflate the concepts of defense and points allowed throughout this post — was 2.2 standard deviations above average in points allowed, one of just ten teams to ever produce such a result.
So how do we get there? Well, Seattle allowed 14.4 points per game during the regular season. The league average was 23.4 points, which means that Seattle’s defense was 9.0 PPG better than average. The standard deviation of points per game among the 32 NFL defenses in 2013 was 4.08 points per game; therefore, Seattle has a Z-score of 2.20, because the Seahawks allowed points at a rate that was 2.20 standard deviations better than the mean.
Today, I wanted to do the same analysis but adjust for strength of schedule, by deriving offensive and defensive SRS grades. Of course, Pro-Football-Reference has published offensive and defensive SRS grades for awhile, but I decided to crunch the numbers on my own and see if they matched up with what Neil and Mike did (they did). For the uninitiated, SRS stands for Simple Rating System, which is simple to understand but a bit complicated to derive. The SRS is simply margin of victory (or, in the case of offenses and defenses, margin of production above league average) adjusted for strength of schedule. The key is using an iterative process, where, in Excel, we adjust the ratings hundreds of times; after all, to adjust for SOS, you have to adjust for the SOS of each opponent, and the SOS of each opponent’s opponent, and so on.
The table below shows the top 200 scoring defenses since 1932. Here’s how to read the 2002 Bucs line. That season, Tampa Bay allowed 9.4 points per game less than league average. The average defense the Bucs faced — using the iterative method to derive SOS grades — was 0.4 points above average. Therefore, Tampa Bay is credited with an adjusted rating of 9.8 PPG better average. The standard deviation of defensive ratings in the NFL in 2002 was 3.45, giving the Buccaneers a Z-score of 2.83, the highest ever. The table below is fully sortable and searchable, and shows the top 200 defenses. [click to continue…]
After 15 weeks, I wrote that Seattle’s pass defense looked to be one of the most dominant since the merger. With the regular season now over, and the Seahawks getting ready for their first playoff game, I wanted to revisit this question and slightly tweak the methodology.
We begin with the base statistic to measure pass defenses, Adjusted Net Yards per Attempt. Team passing yards and team passing yards allowed, unlike individual passing yards, count sack yards lost against a team’s passing yards total. So to calculate ANY/A on the team level, we use the formula (Passing Yards + 20*TD – 45*INT) divided by (Attempts + Sacks). The Seahawks allowed just 3.19 ANY/A this year, which was 1.20 ANY/A better than any other defense this season. In fact, it was so good that it enabled Seattle to easily post the best ANY/A differential (offensive ANY/A minus defensive ANY/A) in the league, too. The Seahawks 3.19 average is the 4th best average in the least 20 years (behind only the 1996 Packers, 2002 Bucs, and 2008 Steelers). But what makes Seattle’s accomplishment more impressive is the passing environment of the NFL in 2013.
When I graded the Seahawks three weeks ago, I defined the league average ANY/A in the customary way: the ANY/A average of the passing totals of the league as a whole. This time around, I decided it would be more appropriate to (1) exclude each team’s own pass defense when calculating the league average, and (2) take an average of the other team’s ANY/A ratings, as opposed to taking an average of the totals. In 2013, the other 31 pass defenses allowed an average of 5.98 Adjusted Net Yards per Attempt. That means Seattle allowed 2.79 fewer ANY/A than the average team this year: that’s better than every defense since 1990 other than the 2002 Bucs.
Next, I calculated the Z-Score for each pass defense. The Z-Score simply tells us how many standard deviations from average a pass defense was. The standard deviation of the 32 pass defenses in 2013 was 0.95, which means the Seahawks were 2.93 standard deviations above average. That’s the 4th best of any defense since 1950.
[click to continue…]
In 2005, several key changes happened in Dallas. Bill Parcells was hired as head coach in ’03, but he didn’t implement a scheme shift right way. After Dallas ranked 27th in points allowed in ’04, though, changes were necessary. With two first round picks, the Cowboys selected 3-4 outside linebacker DeMarcus Ware and 3-4 defensive end Marcus Spears. Dallas also signed Jason Ferguson, who had played nose tackle for Parcells with the Jets. With the pieces in place, Dallas ran a 3-4 defense each of the last eight seasons. Ware has become one of, if not the, greatest 3-4 outside linebackers of all time. But after eight years of Parcells, Wade Phillips, and Rob Ryan, Dallas is returning to its 4-3 roots under Monte Kiffin.
Kiffin, of course, is most famous for the outstanding defenses that he and Tony Dungy created in Tampa Bay; the Tampa-2, after all, has became part of football nomenclature. But I don’t want to go into whether the Cowboys are well-positioned to switch fronts (they’re not) or who will play what role in 2013 (Ware and Anthony Spencer are moving to defensive end, Jay Ratliff will move from NT to DT, and newly rich Sean Lee will play as a true middle linebacker, and he might be even more valuable in this system). Instead, I want to take a 30,000 foot view.
In 1974, the 3-4 defense was introduced to the NFL by Bum Phillips in Houston, Lou Saban in Buffalo, and Chuck Fairbanks and Hank Bullough in New England. I thought it would be interesting to see how teams that switched fronts fared in their first season. On caveat: I wanted to exclude schizophrenic teams like the current Bills (4-3 defense in 2009, 3-4 in 2010, 4-3 in 2011 and 2012, and now a 3-4 again in 2013). According to my records, 74 teams in NFL history have switched from a 4-3 to a 3-4, or vice versa, after running the same front for the three prior years.
[click to continue…]
For eleven straight years, I’ve written an article called “Defensive Team By Committee.” This year’s version is up at Footballguys.com (subscriber only).
Fantasy defenses are inconsistent from year to year, making it difficult to predict which defenses and special teams (D/STs) will excel. And, at least in theory, the teams available at the ends of your drafts should provide less rewards. So how do you get great production out of the position while saving your most important draft picks?
We spend countless hours analyzing team offenses, and relatively few thinking about team defenses. But an average defense against a bad offense will do just as well as a great defense against an average offense. The key to the DTBC system is to find two teams available late in your draft whose combined schedule features predominantly weak offenses. By starting your defense based on matchups, your D/ST will generally face a weak offense, meaning your D/ST position will score lots of fantasy points.
You can read my two picks, along with a ranking of all 496 combinations, here.
For you iPad users our there, I’ll also recommend the $4.99 Footballguys Fantasy Football Magazine Draft Kit, an awesome resource at a super cheap cost. That includes the Draft GM Kit, which you can separately order if (like me) you don’t have an iPad but do have an iPhone. Both products will also be available on Android very soon, if not already by the time you read this. You can receive all Footballguys updates by signing up on the Free Footballguys Daily E-mail list.
I used Footballguys.com’s scoring system in the Footballguys Players Championship to calculate every performance by a fantasy D/ST since 1940. Here it is:
- 1 point – Every sack
- 2 points – Every team takeaway (interception or fumble recovery)
- 6 points – Every TD (via interception return, fumble return, punt or kickoff return, blocked FG return, missed FG return, blocked punt return)
- 5 points – Every safety
- 12 points – Every shutout
- 8 points – Allowing between 1- 6 points
- 5 points – Allowing between 7 – 10 points
Team Defense/Special Teams
Because I decided to use the official scoring designation for every play and chose not to rewatch every game in NFL history, there is one error that will come up in every few hundred games. Occasionally, an offense will score a touchdown on its own fumble recovery and that goes down in the gamebooks as a fumble recovery just like a defensive touchdown. So, be warned, these are unofficial fantasy scores.
As it turns out, Seattle’s game against Arizona comes in tied for 10th place. Incredibly, the best performance by a fantasy defense — a whopping 52 points — came in a Steelers-Browns game but wasn’t delivered by Pittsburgh. The came in the 1989 season opener, and after losing 41-10 the following week, Pittsburgh rebounded to finish 9-7 and make the playoffs. In 1950, the New York Giants also scored 52 fantasy points against the Steelers. New York scored 18 points in that game — 2 safeties, two fumble return touchdowns — and forced 9 turnovers and 7 sacks. The table below lists the best performances by a fantasy defense:
[click to continue…]
I broke down each of the NFL and AFL champions since 1950 into three categories:
- Pass Efficiency, measured by a modified version of ANY/A. The formula was (Passing Yards + 10*TD – 22.5*INT – Sack Yards)/(Pass Attempts + Sacks). This strikes a middle ground between traditional ANY/A and NY/A.
- Rushing Success, according to the following formula: (Rushing Yards + 10*RTD + 5*Rushing1stDowns)/(Carries).
- Defensive Rating, based on the number of offensive touchdowns scored by their opponents.
There are ways to quibble with those categories, and I won’t begrudge anyone who does. After giving each team a rating in each category, I calculated how they compared to the league average in each season. In all cases, the average is 100%, and a number higher than 100% means better.
Here’s what each of the columns mean, from left to right. In 2011, the New York Giants won the Super Bowl; they allowed 43 touchdowns to opposing offenses, averaged 7.6 in my modified version of ANY/A, and averaged 4.9 adjusted yards per carry. The next three columns show how New York ranked relative to league average. By allowing 43 scores, the Giants D was well below average, putting them at 83% of the average mark; they were 25% better than average at passing, but only 86% of league average efficiency in the running game. Since the Giants highest rating came in the passing category, they are listed in the Identity column as a Passing team.
[click to continue…]
[Note: I’m scheduled to appear on The Bobby Curran Show on ESPN 1420 at just after 2:00 today. If you’re interested, you can listen here.]Rex Ryan is the Tim Tebow of coaches: whatever he says tends to get magnified. I was sitting a few feet from Ryan when he made his latest controversial comment. Keyshawn Johnson asked Ryan if having a former head coach in Tony Sparano now coaching the offense would allow him to focus more on the defense. Ryan said it would, although Ryan previously vowed to also be more involved with the offense. The next question asked about Ryan’s confidence, and he said he had a lot of confidence in himself and his coaching staff. He went on:
Now, I wasn’t even in the defensive meeting last night, but I have complete faith and trust in the coaches we have. As I said, it’s easy for me to say I’m the best defensive coach in football. Now that’s saying something, because Dick LeBeau’s pretty (darn) good, Bill Belichick is pretty good. But that’s the way I’ve always believed. And you know what, I believe it because of the guys I coach with, there’s no doubt about that, and the guys that I’ve coached. That’s the truth, and that’s how I feel. I’m going to be more involved over there, calling games or whatever. Obviously, Mike Pettine, that’s my right hand guy, he’s always been my right hand guy and that’s the way it’s always going to be.
Not that inflammatory, is it? In any event, Ryan also issued a call to the media on Saturday, and if you’ve ever read this blog, you know he got my attention with what he said:
I’m still waiting to see somebody put the stats up there, because I know I’m crazy, but go ahead and just put them out there one day, since I’ve been a coordinator and head coach, I dunno where I’d rank…I really don’t even know the answer…Now watch Dick LeBeau get me.
Well, Rex, I’ll put the stats out there for you. Presumably we want to compare Ryan to all current head coaches (with defensive backgrounds) and defensive coordinators in the league. There are only 25 defensive coordinators to examine, as sevens teams do not have coordinators with any relevant track record. Both Missouri teams are actually without defensive coordinators this year: In Kansas City, Romeo Crennel will be head coach and defensive coordinator, while in St. Louis, the Rams are going with a committee approach to replace the suspended Gregg Williams. In addition, five men will be first-time defensive coordinators in 2012: Matt Patricia in New England, Kevin Coyle in Miami, Alan Williams in Minnesota, Jason Tarver in Oakland and John Pagano in San Diego.
[click to continue…]
Thirty years ago, the NFL began officially recording defensive player sacks. Prior to 1982, all teams kept their own individual sack data, but those records (with few exceptions) have never been verified. As a result, it’s an unfortunate reality that for much of NFL history, we simply do not have reliable sack data for individual defensive players.
Three times, Deacon Jones produced 20+ unofficial sacks in the 1960s.1 In 1967, Raiders defensive end
Ben Davidson Ike Lassiter had 17 sacks2 in the AFL. Jack Youngblood and Jim Katcavage both led the league in sacks on two different occasions in the pre-1982 era.3 Cincinnati Bengal Coy Bacon has been credited with 21.5 unofficial sacks during in 1976. The first team to record 60 sacks in a season was the ’57 Bears, and we can be sure that Doug Atkins recorded more than his fair share of that number. For players like Gino Marchetti, Norm Willey, and Len Ford, even unofficial records weren’t kept during their time, leaving us unsure as to who is the true sack king.
It’s important to remember that just because we don’t have official sack data before 1982 doesn’t mean there were great sack artists before then. But that’s a topic for another today. So while we can’t precisely measure how the forefathers of the game played, we do have official data for the last 30 years. So who has been the best pass rusher of the last three decades?
Using total sacks isn’t a fair method to current players, or to those players who chose to retire instead of sticking around to compile six-sack seasons. So if we want to measure sack dominance, we can’t simply look at total sacks any more than we can grade running backs by looking at career rushing yards. One method I like that I’ve used before is sacks over one-half sack per game. This makes 8 sacks in a 16-game season the bar; a player only gets credit for their production over that level. This means that 12 sacks in a 16-game season brings a value of +4.00, while 16 sacks is twice as valuable at +8.00.There’s no great reason to choose 8 over 6 or 10 or any other number. I chose 8 because it feels right, but I don’t claim that it’s based on anything other than my personal, subjective preference.
[You can find lots of websites previewing each team as we head towards the 2012 season. You won’t find that at FootballPerspective.com, but instead, I’ll share some random thoughts on each franchise based on well, whatever springs to mind. We’ll kick things off with look at the San Francisco 49ers.]
The 49ers are an interesting team to me because they seem like the ideal candidate to regress. Generally, teams that make huge jumps in one season are better candidates to fall back to the pack than elite teams with a history of success. Additionally, defensive teams are generally less likely to retain their success than offensive teams. But since I don’t expect you to just believe me…
I looked at all teams since the AFL-NFL merger in 1970 that won at least 75% of their games (San Francisco went 13-3 last year) and then separated them based on their records in the prior season (the 2010 49ers went 6-10). There were 155 of them, and how they performed in the year before (Year N-1) their elite season was relevant in determining their record in the year (Year N+1) after that big season. The table below breaks down the teams based on their winning percentages in Year N-1 (for our purposes, that’s 2010 for the 49ers) and then shows how well they performed in Year N+1 (for our purposes, the 2012 49ers):
|Year N-1||# of Tms||N-1 Win%||N Win %||N+1 Win %|
Just so we’re all on the same page, the top row of that table informs us that of the 155 teams to win at least 75% of their games, 24 of them won over 80% of their games in Year N-1. On average, those teams won 86.3% of their games in Year N-1, 79.7% of their games in Year N, and then 67.2% in Year N+1. The 49ers would represent a team in the bottom row. There have been 25 teams like the 2011 49ers who won at least 75% of their games after having a losing record the prior year (on average, those teams won just 37% of their games – just like the 2010 49ers); in the following year (e.g., the 2012 49ers) those teams won just 53.6% of their games.