Article co-authored by John Shirley

Because there are so few games in a season, stats can be skewed quite a bit if you face a particularly favorable or unfavorable matchup. The two most recent six-sack games, from Adrian Clayborn in 2017 and Osi Umenyiora in 2007, both came against backup left tackles. Their full-season numbers were inflated thanks to their ability to capitalize on a juicy matchup.

To that end, Sports Info Solutions has tried to find ways to evaluate player performance within the context of the opposition they’ve faced. Two examples of this strategy at work are Adjusted Blown Block Rate and Adjusted Pressure Rate, which adjust pass blocking and pass rush performance for the strength of opposition faced.

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Adjusted Blown Block Rate

First, let’s establish what Blown Block Rate is. An offensive lineman’s Blown Block Rate is how often he allows the defender to physically beat him and disrupt the play within the first few seconds of action. This could include run blocking or pass blocking, but here we’ll stick to pass blocking. Because blocking on screens doesn’t work the same way as typical pass plays, for the purpose of Adjusted Blown Block Rate we exclude them as well.

Blown Block Rates typically range from about one to six percent, which should indicate that we’re talking about fairly obvious failures to execute. And those failures have dramatic impacts. Even a single blown block on a pass play changes its average Expected Points Added (EPA) by more than half a point per play.

Average EPA by Number of Blown Blocks, 2019 Pass Plays

Blown BlocksPlaysAvg EPA
0200400.17
12710-0.51
2238-0.86

As for the “Adjusted” part, the calculation takes a player’s Blown Block Rate and adjusts it using a quality-of-competition multiplier that’s calculated for each defensive team against each offensive line position (plus tight end). 

If Team X forced 10% more blown blocks than their opponents typically yielded, but those opponents yielded 20% fewer blown blocks than their opponents typically forced, Team X’s defensive adjustment would be 1.15 / 0.80, which comes out to 1.375. That means, taking into account strength of schedule, Team X’s defense forced 37.5% more blown blocks than average.

From there, you just take a player’s Blown Block Rate and divide it by the defensive adjustment. So a player who yielded a Blown Block Rate of 4.4% against Team X would have an Adjusted Blown Block Rate of 4.4 / 1.375, or 3.2%. His performance looks quite a bit better on account of his defensive opponents being rated so highly.

With that, here are the leaders in Adjusted Blown Block Rate by position. Every list has a minimum of 300 pass blocking snaps at that position (excluding screens).

Adjusted Blown Block Rate Leaders at Center, 2019

PlayerTeamBBRAdj BBR
Brandon LinderJaguars0.58%0.53%
Connor McGovernBroncos0.53%0.56%
JC TretterBrowns0.68%0.63%
Weston Richburg49ers0.78%0.69%
Rodney HudsonRaiders0.79%0.79%

The Jaguars’ Brandon Linder ranked second in BBR, but receives enough of a bump from facing more difficult competition that he ranked first in Adj BBR among centers. Linder faced six of the top 10 interior pass rushers by Adjusted Pressure Rate this season and still managed an impressive season. 

Adjusted Blown Block Rate Leaders at Guard, 2019

PlayerTeamBBRAdj BBR
Zack MartinCowboys0.46%0.43%
Kevin ZeitlerGiants0.78%0.67%
Joel BitonioBrowns0.85%0.73%
Marshal YandaRavens0.84%0.74%
Richie IncognitoRaiders0.72%0.75%

It should not be surprising that Cowboys left guard Zack Martin tops the list in any offensive line metric, as he is universally regarded as one of the best in the league. Martin was voted as a first-team All-Pro by AP and was regarded as the top guard overall by SIS’s Total Points metric. As for his level of competition, having to face the likes of Aaron Donald, Kenny Clark, and Fletcher Cox twice should tell you all you need to know. 

Adjusted Blown Block Rate Leaders at Tackle, 2019

PlayerTeamBBRAdj BBR
Andrew WhitworthRams0.95%0.71%
Trent BrownRaiders0.65%0.77%
Duane BrownSeahawks1.18%0.97%
Ronnie StanleyRavens1.32%1.24%
Lane JohnsonEagles1.20%1.41%

Andrew Whitworth might be on the back end of his career at 38 years old, but he is still performing at an elite level. He tied for the lead among all offensive linemen in Total Points and by ESPN’s Pass Block Win Rate he ranked as the second-best offensive tackle. He received a large boost from our adjustment due to the fact that he faced 10 of the top 20 edge rushers, including four of the top five — the fifth was his own teammate Samson Ebukam

Adjusted Pressure Rate

The calculation for Adjusted Pressure Rate is the same as for Adjusted Blown Block Rate, just flipped on its head. Instead of looking at the Blown Block Rate allowed or forced for each offensive line position, we look at the Pressure Rate allowed or forced for each defensive line position. The calculation splits pass rushers based on how they align (across from the center, guard, tackle, or wider), but to keep samples large enough we’re bundling them here into interior and edge rushers.

With that, here are the leaders in Adjusted Pressure Rate on non-screen plays, with a minimum of 200 rush snaps.

Adjusted Pressure Rate Leaders, Interior Rushers, 2019

PlayerTeamPressure RateAdj Pressure Rate
Aaron DonaldRams12.8%12.8%
Cameron HeywardSteelers12.4%11.9%
Grady JarrettFalcons12.2%11.6%
Chris JonesChiefs10.8%11.5%
Leonard WilliamsGiants10.4%10.8%

Aaron Donald is really good at football. And that’s all we have to say about that. 

Chris Jones, who missed time earlier in the postseason for the Chiefs but will be healthy in time for the “Big Game,” gets a little boost into the tier behind Donald because he lined up across from above-average blockers more often than not.

Adjusted Pressure Rate Leaders, Edge Rushers, 2019

PlayerTeamPressure RateAdj Pressure Rate
Nick Bosa49ers17.7%18.5%
Matt JudonRavens18.0%17.4%
Samson EbukamRams16.1%17.3%
T.J. WattSteelers17.1%17.1%
Cameron JordanSaints16.9%16.6%

Nick Bosa’s season has been dominant for any player, much less a rookie. He receives a positive adjustment on top of an already impressive 17.7% pressure rate. In his Super Bowl matchup with the Chiefs, watch for Bosa to take advantage of left tackle Eric Fisher, who ranked 22nd of 32 left tackles with at least 300 pass snaps in Adjusted Blown Block Rate in the regular season.

The Final Word

Over the course of a year, a few choice matchups can cause a player’s stats to be a bit inflated. Using adjustments to existing stats (especially adjustments that focus on the players who are directly interacting with the players of interest) can help us wade through interactive effects that pervade football analysis.

As you can tell from the tables above, on a season level those matchups don’t wildly change our conception of a player. In a one-game sample, though, a single mismatch in the trenches can blow up your game plan. No one expects Nick Bosa to rack up six sacks next Sunday, but don’t be too surprised if you see him come close.