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Concentration Index and Defensive Sacks

Are sacks more highly concentrated among a few players now? Look at the 2016 Raiders: Khalil Mack, who won the Defensive Player of the Year award by one vote over Von Miller, had 11 sacks. But Mack and Bruce Irvin (7.0 sacks) were the only Oakland defenders to record more than three sacks last year, and only six Raiders finished the year with a sack. In Atlanta, Vic Beasley led the NFL with 15.5 sacks, but only eight other Falcons had a sack, and no other Falcon had more than five. Meanwhile, the ’86 Oilers had 17 players record at least one sack and no player with more than five sacks!

In 2014, J.J. Watt had 20.5 of Houston’s 38 sacks. And in 2012, Aldon Smith had just over half of the 49ers sacks, too. But are things really getting more concentrated? Memory can play tricks on us: after all, in 1989, Tim Harris had 19.5 sacks for the Packers, which represented 57% of all Green Bay sacks that year.

As it turns out, the Raiders and Falcons weren’t great examples to measure the modern NFL. They were the two most concentrated teams in the NFL last year in terms of sacks. Let’s look at the Raiders sack totals more closely, and use the same methodology we’ve used the last few days (also known as the Herfindahl index):

PlayerSacksPercSquared
Khalil Mack1144%19.4%
Bruce Irvin728%7.8%
Denico Autry312%1.4%
Stacy McGee2.510%1.0%
James Cowser14%0.2%
Dan Williams0.52%0.0%
Team25100%29.8%

Oakland has a concentration index of 29.8%, which is the 4th highest since 1982 behind the ’89 Packers (35%), 2014 Texans (33%), and 2012 49ers (31%). The 2016 Falcons are at 26%, and the table below lists every team in the league:

RkTeamCon Ind
1OAK29.8%
2ATL25.6%
3MIA20.2%
4KAN19.3%
5ARI18.6%
6MIN18.5%
7DEN18.4%
8SEA17.4%
9CIN17.3%
10BUF17.1%
11SDG16.9%
12WAS16.9%
13IND16.7%
14DET16.1%
15TEN15.9%
16GNB15.7%
17NOR15.4%
18HOU14.7%
19NYJ14%
20LAR13.9%
21JAX13.7%
22CHI13.7%
23NYG13.5%
24BAL13.4%
25TAM12.4%
26PHI11.8%
27SFO11.8%
28NWE11.3%
29CLE11.2%
30DAL11%
31CAR9.7%
32PIT8.4%

The Steelers last season had 15 players record at least one sack, with 38-year-old James Harrison leading the team with 5 sacks. Pittsburgh was in the top third of the NFL in sacks last year, and that’s despite having a very decentralized way of getting to the quarterback. Meanwhile, the Panthers had the 2nd most sacks in the NFL with 47, and the 2nd least-concentrated pass rush: 18 Carolina defenders had a sack, but none had double digits. In other words, there’s more than one way to sack a quarterback.

Overall, the NFL average concentration index for sacks was 15.6%.  Since 1982 (and excluding the strike 1987 season), the NFL average was…15.4%.  Other than a relatively concentrated period in the early ’90s, this statistic has been remarkably consistent over time.  And there doesn’t appear to be much in the way of a trend:

A result of ‘no result’ is often just as interesting as one showing the opposite: yes, it would be interesting if sacks were becoming more concentrated (teams are scheming around one or two elite talents?) or less concentrated (defensive schemes are becoming more complex and bringing pass rush from all over?), but a no change result brings all sorts of questions, too. Why do you think this is?

  • Four Touchdowns

    I like these kinds of articles.

    This kinda makes me think more about an overall efficiency rating for defenses, like ANY/A is for QBs / Passing Offenses.

    I guess Interceptions and Sacks would probably be the equivalent of TDs?

  • sacramento gold miners

    The name of Tim Harris doesn’t come up much today, but there was a time when he was a nightmare for offenses to handle. A two-time All Pro selection, Harris amassed 75 sacks through his age 28 season. But injuries caught up to Harris, and he wasn’t close to the same player later.

  • MattHat121

    Double teams. Easy way to stop the dominate pass rushers.

    Separate point: I would say the bottom six teams on that list all have been accused of having “no pass rush.” That phrase is sometimes used simply to point out the team doesn’t have a big name or high-sack-total OLB or DE. And it also typically means those teams are assumed to be looking for pass rush help in the draft. Here are their 2017 first draft picks:

    SFO – Solomon Thomas (DE)
    NWE – Derek Rivers (DE)
    CLE – Myles Garrett (DE)
    DAL – Taco Charlton (DE)
    CAR – Christian McCaffrey (RB)
    PIT – TJ Watt (OLB)

    That’s a pattern! With the exception of CAR, all took pass rushers. Granted, it was a great class for pass rushers, and other teams higher on this list did the same (ATL took Tak McKinley, MIA took Charles Harris), but it seems those bottom 6 are looking for help to improve their pass rush, so this stat suggests dilution is a symptom of a problem teams want to solve.

    • MattHat121

      Not including NWE’s third round pick, of the 8 DE/OLBs taken in first round, those bottom teams counted for 5 of them. Including NWE’s pick, that’s 6 of 9 first picks that were OLB/DE taken by the bottom 6 teams with the lowest concentrated sack percentage.

    • Phil

      That’s an interesting thought

      as offenses spread out more, do they double team pass rushers less?

      and deal with the pass rush by throwing hot more?

      there are a few ways that could result in different sack concentrations

      as offenses keep RB and TE in to block, there are fewer guys in routes that need to be covered, so it makes more sense to send extra guys in the rush, thus more guys out there who can pick up sacks

      sack concentration seems like a function of defensive philosophy, a defense that does a lot of blitzing will have a lower sack concentration than a defense that wants to blitz less, cover everyone, and rely on their front 4 for the pass rush

      if offenses are getting better at throwing hot/quickly, are only the best pass rushers able to get to the QB before the offenses are able to get rid of the ball? Thus changing the concentration