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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:

I’m sure none of you reading this are surprised by the teams that show up here; all the heavy hitters are there, including the recent Seattle defenses. As noted, dynasties can be hard to define, but we can be sure that being consistent is one of the key ingredients, and the Seahawks defense has certainly been that. Below is a table showing how they’ve ranked in various metrics in the past 5 years:

Pretty impressive, and no doubt, that’s a dynasty. How does their 5-year run compare to the two legendary teams that are ahead of them in that category?

While the Seahawks don’t have those absolutely “elite” regular seasons — the Bears and Steelers both have two years of +8.0, and the Seahawks have none — they have the highest “worst” year out of the three. To underscore how remarkable their run has been, it’s worth taking a look at their contemporaries. Below is the Seahawks’ 5-year run compared to the current 5-year runs of six other teams that have had (or have) good defenses:

Carolina had a fantastic 2013, only to drop to average the following few years; the 49ers were great in the Harbaugh years, dipping in 2014 and then mediocre in 2015; the Bengals, Chiefs and Cardinals have been consistently good but not great, and Denver has two average and below average years sandwiched in between three good/great years. It’s not easy to be consistently great, year after year.

I’ll be watching the Seahawks closely this year. If they can hold teams to around 15 or 16 points per game (no easy task), they’ll replace the Bears as having the best 6-year dynasty, which, to me, is historically significant. Over the last five years, Richard Sherman, Bobby Wagner, and Earl Thomas have been three of the top defensive players in the NFL: Sherman and Thomas are two of just seven defenders with three first-team All-Pro nods since 2012, and Wagner ranks fifth in AV among all defensive players over the last five years.

A few other comments:

  • This analysis is doing a big disservice to the Minnesota Vikings by making 1970 the cut-off year. In 1969 the Vikings DSRS was 10.6, and I’m sure if we remove “non-defense allowed” scores that number wouldn’t change much. Including that 1969 season in the survey puts Minnesota at the top of the “Elite” ranking, and would easily give them the best three and four year runs. For future posts, I’ll take a stab at incorporating pre-merger years.
  • You might be surprised to see the Ravens showing up to the party so late – they don’t break into the table until we hit the 13-year run. There’s no doubt they are a defensive dynasty, but they had a lot of ups and downs, with great years interspersed with some down years. For example, their 5-year run surrounding their Super Bowl win in 2000 looks like this:

As noted, it’s hard to be continually be great, year after year, for any length of time.

  • The 1970s Dolphins are another team that shows up late; as good as they were, they just weren’t as dominant as the other dynasties. If I included the 4th and 5th best dynasties, they’d most likely start showing up in the 4-6 year ranges.
  • Other dynasties that aren’t listed but would appear if I showed more than just the Top 3:
    • Jacksonville Jaguars, 2004-2007
    • Los Angeles Rams, 1973-1978
    • New Orleans Saints, 1986-1992
    • New England Patriots, 2003-2010
    • New York Giants, 1981-1990
    • Pittsburgh Steelers, 1990-1996
    • San Francisco 49ers, 1981-1992
  • I didn’t run the numbers, but my hunch is that if we keep stretching the length of the dynasty out, the Pittsburgh Steelers would probably continually be at the top once we pass 25 years or so. They really have three distinct defensive dynasties, and when these connect, I don’t see any team topping them:
  • If you’re thinking playoff success should be considered when ranking dynasties, you’re 100% correct. I’m working on a way of including that; maybe some kind of point system or perhaps just add in points allowed above expectation for each playoff game, etc. Definitely worth doing for something like this.

Thanks for reading, would love to hear your thoughts.

  1. Their definition of “best” being their ELO ratings. []
  • sacramento gold miners

    I do think the mark of a defensive dynasty is how they perform in the postseason, where they are often facing elite offenses on the bigger stage. In the three team, historical five year run category, the 1972-76 Steelers only fell in the divisional round once. The 1984-88 Bears never returned for a second Super Bowl trip, and the 2012-16 Seahawks had that epic fourth quarter defensive collapse against New England in the 2015 SB.

    • Richie

      The 2006 Ravens had perhaps the best defense in the league. In the playoffs, they held the Colts (one of the best offenses that year) to 261 yards and 5 field goals.

      But their offense let them down and only scored 6 points, and they lost the game. Doesn’t seem fair to penalize the defense for that.

      (Two of the Colts’ field goals came off Raven turnovers, including one where the Ravens were deep in Colts territory in the second quarter with a chance to take the lead.)

      • sacramento gold miners

        Couldn’t agree more about the 2006 Ravens, Baltimore has had a strong defense for years. They did a great job against Peyton Manning in that game, but Steve McNair and the offense couldn’t get it done at home.

        • Mark Growcott

          The Ravens had a terrific Defense in 2006, they were No.1 in both Points allowed and Yards allowed and it wasn’t even close. That’s what made watching that game so frustrating, the Ravens who had the home field advantage and were 4 point favourites, intercepted Manning twice and kept the Colts without a TD and still couldn’t take advantage. This was against a Colts team that was a distant last in Rushing Yds allowed during the Regular Season (173 Yds/Gm) and the Ravens had a season low 20 Rushing attempts during that game with Lewis only getting 53 Yds. It was a pathetic performance by the Ravens Offense that day.

          I recall the Colts went into that Post Season far from being favourite to win the SB with the aforementioned worst Rushing Defense in the League. In the Wildcard game the Chiefs with Larry Johnson were expected to have a field day but the Colts kept them to a miserly 44 Yds of which Johnson only had 32. The Colts Offense looked decidedly ordinary in those first 2 Playoff games where Manning threw a total of 5 INTs.

          • Tom

            Agreed, the Ravens in 2006 were top notch, no question about it. And to hold that offense to 5 field goals…as noted, they really, *really* need the offense to do something…

            Kind of a weird playoff run for the Colts…their historic offense, and Manning in particular, sputtered for those first two games, did great against the Pats, and then were just OK against the Bears.

      • Tom

        And this is where things get sticky when I try to include the playoffs…we certainly want to reward teams with playoff success, but we also don’t want to ding teams too much for a single loss. The question is interesting…what do we do with the 2011 Giants? They had the worst regular season DfSRS of any Super Bowl winner at -1.5, but in the playoffs, they were solid, allowing 13.5 points per game which is about 7 points above average. Anyway, for a future post, the playoffs need to be included if we’re going to talk about dynasties…

      • Tom

        The Ravens had a DfSRS of 6.6 that year, which is really, really good. After adjusting for SOS, the Colts offense was putting up about 27 points per game. The Ravens held them to 15, meaning 8 points above expectation. To me, this is a clear victory for the defense. But still..Baltimore didn’t move on. So how do we figure that in? Should they be ranked higher than a team that goes deeper in the playoffs? Hard to say…

        • Richie

          In my opinion, if you are trying to determine the dynasty of only part of a team, you can’t weigh playoff success very heavily because one side of the ball only has about 45% impact on the outcome of the game.

          If you want to talk about team dynasty, then I think playoffs can be weighted more heavily.

          • Tom

            That’s kind of what I’m thinking…include the games and perhaps very *slightly* weight them. The result would be something like the 1970’s Dolphins overtaking the late 1990’s Bucs in a category or two. In 1972 the Dolphins defense allowed an average of 8 pts/game in the playoffs, in 1973 they allowed about 10 pts/game. This is really good, even for the ’70’s, and it improves their standing as a dynasty no doubt.

  • Ryan

    With a good 2017, I believe Seattle could make both the 6-year and 7-year top three. Their 2011 at +2.0 was decent.

  • Richie

    Surprised that the 84 and 85 Dolphins crept in to your list. But it looks like the 84 defense was ranked 7th in points – which is better than my memory of them.

    • Tom

      The Dolphins kind of surprised me (but probably shouldn’t have I guess). We know about how great they were in the early 1970’s, but they were solid from 1977-1983 as well.

  • Can’t wait till you take this back to the Cleveland dynasty of the 40s and 50s.

    Also, and this relates to the cold weather QB talks we have whenever two certain QBs are mentioned in the same post, I don’t think it’s a coincidence that many of the great defensive runs came from teams in cold or poor weather cities.

    • Tom

      Yeah, I guess it’s time to get off this “since the merger” thing.

      Agreed about the cold weather…Pittsburgh, Minnesota, Chicago, Denver, Seattle, Baltimore…and then Tampa Bay and Miami. Would be cool to throw in some kind of “weather factor” or home field advantage tweak. Man, that would take some TIME though…