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Just above these words, it says “posted by Chase.” And it was literally posted by Chase, but the words below the line belong to Bryan Frye, a longtime reader and commenter who has agreed to write this guest post for us. And I thank him for it. Bryan lives in Yorktown, Virginia, and operates his own great site at nflsgreatest.co.nf, where he focuses on NFL stats and history.


In February, Chase used a regressed version of Football Outsiders’ DVOA metric to derive 2014 expected wins. If you are reading this site, you probably have some familiarity with Football Outsiders and DVOA, FO’s main efficiency statistic. Given the granularity of DVOA, it is no surprise that Year N DVOA correlates more strongly with Year N + 1 wins (correlation coefficient of .39) than Year N wins does (correlation coefficient of .32).

By now, even casual NFL fans probably have at least heard of Pythagorean wins, and regular readers of this site are certainly familiar with the concept. Typically, an analyst uses Pythagorean records to see which teams overachieved and underachieved, which can help us predict next year’s sleepers and paper tigers. Well, I wondered what would happen if we combined the two formulae to make a “DVOA-adjusted Pythagorean Expectation” (or something cooler sounding; you be the judge).

Going back to 1989, the earliest year for DVOA, I used the offensive, defensive, and special teams components of DVOA to adjust the normal input for Pythagorean wins (points). Because DVOA is measured as a percentage, I adjusted the league average points per team game accordingly (I split special teams DVOA between offense and defense). Let’s use Seattle, which led the league in DVOA in 2013, as an example.

In 2013, the league average points per game was 23.4. Last year, Seattle had an offensive DVOA of 9.4% and a defensive DVOA of -25.9% (in Football Outsiders’ world, a negative DVOA is better for defenses).  The Seahawks also had a special teams DVOA of 4.7%.  So to calculate Seattle’s DVOA-adjusted points per game average, we would use the following formula:

23.4 + [23.4 * (9.4% + 4.7%/2)] = 26.15 DVOA-adjusted PPG scored

And to calculate the team’s DVOA-adjusted PPG allowed average, we would perform the following calculation: [click to continue…]

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2014 Football Outsiders Almanac

If you’re reading this blog, chances are you already know all about our friends at Football Outsiders and the terrific analysis they provide every year. However, if by some chance you don’t know of them, or maybe you haven’t heard about their outstanding annual book, they now have copies of the 2014 Football Outsiders Almanac available for purchase. The book is jam-packed with FO’s signature data (including game-charting stats), plus the usual stat-geeky essays, team and player previews, and 2014 projections. And it’s not just the NFL, as Football Outsiders has some pretty sharp minds (Matt Hinton, Bill Connelly, Brian Fremeau) covering the college game, too.

For the second year in a row, I have contributed to the Almanac. I wrote team essays for the Giants  and Jets (only one of those teams has a great defense and a terrible offense!), along with player comments for both of those teams. If you enjoy my work here, you’ll probably enjoy reading what I wrote about those teams.

Football Outsiders has been a supporter of Chase Stuart for a while and Football Perspective from the beginning. But don’t confuse this for charity post: the FOA is a great guide, and I’m sure anyone who buys it will be very happy.

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A couple of weeks ago, Brian Burke of Advanced Football Analytics (formerly Advanced NFL Stats) wrote a great post on the value of a first down. From that post, we concluded that the marginal value of a first down is 9 yards, and we’ve previously determined that the marginal value of a touchdown is 20 yards. Therefore, we can create an Adjusted Yards per Carry statistic, which can be calculated as follows:

Adjusted Yards per Carry = (Rushing Yards + 20 * Rushing TDs + 9 * Rushing First Downs) / Rushes

If we use this metric to analyze the 2013 season, how would it look? Last year, the Eagles averaged 5.13 yards per carry and 8.29 Adjusted YPC, courtesy of the fact that the team led the NFL in rushing first downs. Philadelphia also ranked 1st in the NFL in both of those metrics and in overall rushing yards. [click to continue…]

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Estimated DVOA Ratings From 1950 to 2013

For over a decade, Football Outsiders has been publishing its DVOA grades. Last week, Andreas Shepard, a loyal reader of both FO and this site, came up with estimated DVOA ratings going back to 1950. You can read the fine print on how he derived the formula in the Methodology section at the end of this post. Andreas did an excellent job looking at some of the best and worst teams in many different DVOA categories, so you should give his article a read. But to me, at least, the real value of team ratings for over 1600 teams in 8 different categories is as a reference piece. And since the tables I create here are both sortable and easily searchable, I’ve worked with Andreas to present the team ratings in a way to make life easy for the reader. Consider these like an encyclopedia for team ratings, available for you to find the team you’re interested in whenever you like.

Andreas created estimated DVOA ratings for each year from 1950 to 2013 (remember, Football Outsiders has posted actual DVOA ratings published for each year from 1989 to 2013, but I am providing the estimates for each year.) The table below shows all 1638 teams from 1950 to 2013; here’s how to read the table below, which is sorted from best to worst in Total DVOA. The Packers (you can click the link to see Green Bay’s PFR page that year) in 1962, playing in the NFL, rank as the top team in estimated DVOA. That year, Green Bay went 13-1 with a winning percentage of 0.929 and a points differential of 19.1 points per game.

The Packers had an Offensive Pass DVOA grade of 18.9% and an Offensive Run DVOA grade of 23.0%; all DVOA ratings are centered around 0%, so this shows how the Packers were well above average in both offensive measures. For defensive ratings, negative grades are better, and the Packers have an incredible -33.2% estimated Defensive Pass DVOA grade, along with a -8.6% estimated Defensive Run DVOA grade. The Packers’ Total Offensive DVOA grade was 21.4%, the Total Defensive DVOA grade was -20.7%, and the Special Teams DVOA grade was 5.8%. Finally, the Packers have a total estimated DVOA of 47.9%, the best since 1950. If you type “gnb” into the table below, you will see all Packers teams. You can type in any team’s code to see just their teams, or sort the table by any of the categories available.

[click to continue…]

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Projecting Team Wins Using DVOA

For a decade, Football Outsiders has been using advanced analytics to measure and predict team performance. And since the Football Outsiders database now goes back to 1989, I thought it would be worthwhile to test the predictive power of Football Outsiders’ ratings.

If you’re not familiar, FO uses DVOA as its base measure of team strength. The goal here is to use DVOA ratings in Year N to predict win totals in Year N+1. Now, what expectations should we have for DVOA? The fact that the team with the best DVOA in history — Washington in 1991 — won only 9 games the following season is not a knock on DVOA. That was an outstanding Super Bowl team that declined significantly the following year. Ditto the 16-0 Patriots looking less impressive without Tom Brady in 2008. But at a minimum, DVOA must do better at predicting future wins than say, just wins. And it should also do better than Pythagenpat ratings, which only incorporate points scored and points allowed. So does it?

Let’s start with the basics. The best-fit formula1 to project wins in Year N+1 using *only* wins in Year N is:

5.343 + 0.332 * Year N Wins (Correlation Coefficient: 0.32)

And, as shown last week, by using Pythagenpat wins, we get a correlation coefficient of 0.36. So what happens if we instead use Year N DVOA as our input? We get the following best-fit formula:

8.01 + 6.378 * DVOA (Correlation Coefficient: 0.39)

As a result, DVOA does beat both regular wins and the Pythagenpat ratings. Now, what if we use both DVOA ratings and number of wins to predict future wins? As it turns out, the wins variable was nowhere near significant (p = 0.61), which means once we know the DVOA ratings, knowing the number of wins adds no predictive power. In other words, the evidence doesn’t prove that a team with a lot of wins but an average DVOA rating is better than a team with an average number of wins and an average DVOA rating.

But can we improve on DVOA? What if instead of using Team DVOA as our input, we use Offensive DVOA, Defensive DVOA, and Special Teams DVOA? Team DVOA obviously incorporates all three of these elements, but perhaps analyzing team strength on a more granular level will tell us more about the appropriate weights. Keeping in mind that for defenses, a negative DVOA grade means an above-average defense, here is the best-fit formula to predict future wins with those three inputs:

8.01 + 6.779 * OFFDVOA – 5.642 * DEFDVOA + 6.518 * STDVOA

[click to continue…]

  1. Over the period 1989 to 2012, excluding the 1994, 1998, and 2001 seasons. []
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Football Outsiders Almanac

If you’re reading this blog, chances are you already know all about our friends at Football Outsiders and the terrific analysis they provide every year. However, if by some chance you don’t know of them, or maybe you haven’t heard about their outstanding annual book, they now have copies of the 2013 Football Outsiders Almanac available for purchase. The book is jam-packed with their signature data (including game-charting stats), plus their usual stat-geeky essays, team and player perviews, and 2013 projections. And it’s not just the NFL, as Football Outsiders has some pretty sharp minds (Matt Hinton, Bill Connelly, Brian Fremeau) covering the college game, too.

The end of the Almanac includes an Acknowledgments section. For years, Football Outsiders has been nice enough to group me with Doug Drinen and Neil Paine as FO’s “comrades” in the statistical revolution. But this year, they’ve left me out of the Acknowledgments section. Entirely.

That’s because I’ve moved over to the Contributors section. I wrote team essays for the Giants, Eagles, and Jets, along with player comments for the majority of players on those teams. If you enjoy my work here, you’ll probably enjoy reading what I wrote about those three teams.

Football Outsiders has been a supporter of Chase Stuart for a while and Football Perspective from the beginning. But don’t confuse this for charity post: the FOA is a great guide, and I’m sure anyone who buys it will be very happy.

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Interview with Aaron Schatz

Last week, I sat down with Brian Burke and discussed the work he’s done with NFL teams. Aaron Schatz, founder of Football Outsiders, an indispensable resource for fans of advanced football statistics, has been consulting with NFL teams for years. Schatz is also the lead writer, editor, and statistician on the book series Football Outsiders Almanac and writes for ESPN.com and ESPN The Magazine. Below is my interview with Aaron.

Q: Aaron, can you go into specifics on the type of work you do for NFL teams? Do you envision ultimately working for a team?

As far as consulting with teams, I’ve done two different sorts of things. First, I’ve done some in-game decision analysis, some fourth down stuff as well as some analysis on when to accept or decline penalties. Second, I’ve done reports for teams in February that gave analysis of the season with our stats, looking at what issues were likely to statistically regress and what issues really needed to be addressed, along with suggestions for possible free agent signings. Actually, it’s more accurate to say “we’ve done” rather than “I’ve done.” Some consulting I’ve done alone, and sometimes two or three guys on the FO staff work together.

Consulting for teams is great, but as advanced analysis people gradually move into front offices I don’t think I will be one of them. I don’t know about the various other folks who have followed in FO’s footsteps, but my heart has always been with the media, going back to my days running my high school paper, through my time as a radio disc jockey, doing the Lycos 50, and now Football Outsiders. I set out to revolutionize the way people analyzed the NFL, not the way they managed teams. If I end up improving the way people manage teams a little bit too, that’s just extra coolness.

Q: You publish your DVOA rankings every week, one of the most popular football articles on the web. Have you ever gotten flak from a team for them (i.e., how come we’re hiring you, we have a winning record, and you have us 24th!)?

No flak, no. A couple times I’ve had teams that I’ve worked with or that I’m otherwise in contact with ask me why their rating is particularly low in one area. However, unlike a lot of fans, people who work for teams understand that our stats are objective based on a general formula and don’t get tweaked to favor one team over another depending on how we feel each week. I think when people ask me why their team is low in one area, they often ask so that they can improve that area. And when a team hits rock bottom, I mean, they know it. The Jacksonville people don’t need to ask me why the Jaguars are ranked 30th in DVOA, or whatever it is this week. They don’t care as much about their DVOA right now as they do about their DVOA (and record) next year or two years from now. Jim Schwartz has told me he would rather have his defense ranked highly in DVOA than in yards per game. Of course, he’d rather have more wins than either. (In case it’s not clear otherwise, I should point out there are more teams where I’ve got contacts among various coaches and front office people than there are teams that I have actually worked for and received a check from.) [click to continue…]

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