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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:

RkYearTeamCon IndexSacksSack RateN+1Change
11989Green Bay Packers35.2346.7%5.3%-1.30%
22014Houston Texans32.8385.8%7.5%1.70%
32012San Francisco 49ers31386.3%6.1%-0.20%
42016Oakland Raiders29.8254.4%0.0%
52008Indianapolis Colts29.1305.9%5.5%-0.40%
62008Atlanta Falcons29335.8%5.0%-0.90%
71984New York Jets28.7447.9%8.8%0.90%
82001New York Giants28.5468.1%6.4%-1.70%
91999Arizona Cardinals28.3336.3%5.2%-1.10%
102010Indianapolis Colts28.2295.3%5.6%0.20%
112014Kansas City Chiefs27.9467.8%7.2%-0.60%
121994Washington Redskins27.9285.3%5.2%-0.10%
132008Houston Texans27.4255.0%5.2%0.10%
142012Kansas City Chiefs27.3275.5%7.4%1.90%
152012Houston Texans27.1447.0%6.2%-0.80%
161996Arizona Cardinals27285.1%6.5%1.40%
171982Buffalo Bills26.4124.5%6.3%1.80%
182011Dallas Cowboys26.1427.2%6.2%-0.90%
192007Houston Texans26315.4%5.0%-0.30%
202013Indianapolis Colts25.9427.3%7.0%-0.20%
211994Buffalo Bills25.8254.5%7.8%3.30%
221988Green Bay Packers25.7306.0%6.7%0.70%
232016Atlanta Falcons25.6344.9%0.0%
242009Indianapolis Colts25.6345.5%5.3%-0.20%
251993Kansas City Chiefs25.5356.3%7.2%0.90%
262011Minnesota Vikings25.2498.5%6.7%-1.80%
272015Houston Texans24.9457.5%5.6%-1.90%
281988Philadelphia Eagles24.7426.8%10.5%3.70%
292012Dallas Cowboys24.5346.2%5.2%-1.10%
301991Phoenix Cardinals24.5255.3%5.6%0.30%
312005Oakland Raiders24.3366.9%7.7%0.80%
321990Los Angeles Rams24.2305.6%3.8%-1.90%
332010Dallas Cowboys24.2356.1%7.2%1.10%
342007Kansas City Chiefs24.2377.4%1.9%-5.50%
352006Indianapolis Colts24.1245.7%5.3%-0.40%
361989New York Giants24.1397.4%5.7%-1.70%
371990Buffalo Bills24438.6%5.5%-3.20%
382009Denver Broncos23.8397.1%4.4%-2.70%
391994Atlanta Falcons23.6325.2%4.4%-0.80%
402008Miami Dolphins23.4406.8%8.3%1.50%
412003Denver Broncos23.4356.8%7.3%0.50%
422010Baltimore Ravens23.4274.3%8.2%3.90%
431996Kansas City Chiefs23.4315.5%9.6%4.20%
442007Green Bay Packers23.1366.3%5.0%-1.40%
452003Tampa Bay Buccaneers23357.0%9.4%2.30%
462011Kansas City Chiefs23296.0%5.5%-0.50%
471992Philadelphia Eagles23549.6%7.2%-2.40%
482000Pittsburgh Steelers22.7387.0%9.5%2.50%
491986Buffalo Bills22.6365.9%7.1%1.10%
501993San Diego Chargers22.6325.4%6.9%1.50%
Average of Top 5025.834.96.4%6.4%0.00%

On average, these teams had a 6.4% sack rate in Year N, and that didn’t change in Year N+1. Again, there are many other factors to consider, but that’s an interesting result compared to the next table. This shows the 50 least concentrated pass rushes since 1982.

RkYearTeamCon IndexSacksSack RateN+1Change
10571986Houston Oilers8326.1%6.6%0.5%
10562013Cleveland Browns8.2406.2%5.0%-1.2%
10552014Tennessee Titans8.2396.7%7.2%0.5%
10541987San Diego Chargers8.3459.3%6.2%-3.1%
10531997Pittsburgh Steelers8.3488.0%7.8%-0.1%
10522007Cincinnati Bengals8.4213.9%3.3%-0.7%
10512016Pittsburgh Steelers8.4386.1%0.0%
10502007Baltimore Ravens8.4316.1%6.0%-0.1%
10491987Chicago Bears8.46912.1%7.3%-4.8%
10481987Cincinnati Bengals8.5408.1%7.4%-0.6%
10471998Tennessee Oilers8.6305.5%8.8%3.3%
10461984San Francisco 49ers8.6518.5%8.8%0.3%
10452004New York Giants8.7397.9%6.6%-1.3%
10441987Houston Oilers8.9356.6%7.6%1.0%
10431997Dallas Cowboys9387.4%5.8%-1.6%
10421985Houston Oilers9418.2%6.1%-2.0%
10411987San Francisco 49ers9367.3%7.3%0.0%
10401987Washington Redskins9539.1%8.0%-1.2%
10392010New England Patriots9365.6%6.1%0.5%
10382004Washington Redskins9.1407.2%6.1%-1.1%
10372009Cleveland Browns9.1407.1%5.4%-1.7%
10362006Atlanta Falcons9.1376.7%4.5%-2.2%
10352008Jacksonville Jaguars9.2295.9%2.7%-3.2%
10342004Buffalo Bills9.2458.5%7.0%-1.5%
10332015Jacksonville Jaguars9.3365.6%5.7%0.0%
10321987Detroit Lions9.3428.4%8.4%0.0%
10312003Arizona Cardinals9.3214.1%7.0%2.9%
10302001Buffalo Bills9.3347.0%5.9%-1.1%
10292004Philadelphia Eagles9.3457.9%5.5%-2.4%
10282013Oakland Raiders9.3386.5%3.9%-2.5%
10271990New England Patriots9.3338.1%4.2%-3.9%
10262009San Diego Chargers9.4346.2%8.8%2.6%
10251986Miami Dolphins9.5336.4%4.1%-2.3%
10242000Cleveland Browns9.5428.0%7.2%-0.7%
10231995Houston Oilers9.5305.1%6.3%1.1%
10221987Dallas Cowboys9.5509.2%8.1%-1.1%
10212015Pittsburgh Steelers9.6477.1%6.1%-1.1%
10202014San Diego Chargers9.6264.7%5.9%1.2%
10191999New England Patriots9.6427.5%5.1%-2.4%
10182016Carolina Panthers9.7477.1%0.0%
10172014Indianapolis Colts9.7407.0%5.6%-1.4%
10161983Denver Broncos9.7366.4%8.3%1.8%
10152013San Diego Chargers9.7346.0%4.7%-1.3%
10141998San Diego Chargers9.8376.9%6.9%0.1%
10131984Atlanta Falcons9.8377.9%7.3%-0.6%
10121988New York Jets9.8448.6%5.2%-3.5%
10111997Philadelphia Eagles9.8418.1%8.6%0.5%
10101987Green Bay Packers9.8346.8%6.0%-0.8%
10091989Cincinnati Bengals9.8336.4%4.4%-2.0%
10082004Oakland Raiders9.9244.7%6.9%2.2%
Average of Bottom 509.238.17.1%6.2%-0.9%

The pass rushes were a little bit better in Year N at 7.1%, but dropped to 6.2% in Year N+1. Is that statistically significant? Probably not, and a regression on the data as a whole tells us no. We’d probably need to do a deeper dive to draw any definitive conclusions. But if nothing else, just seeing the bottom and top 50 teams in sack concentration makes for an interesting post. For example, the 1986 Oilers had the least concentrated pass rush ever: Houston had 32 sacks from 17 different players!

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