Not all 10-sack seasons are equal in the NFL. Opportunity matters. The likelihood of bringing down a quarterback is a lot higher on a third-and-10 blitz against Daniel Jones than a four-man rush on first-and-10 against Drew Brees. Those chances are not distributed evenly.
That's why we're introducing a new metric we're calling expected sacks. The idea is to determine the likelihood of an average pass-rusher recording a sack on each play, based on the factors around him. The factors for each pass-rusher on every play are:
What position he played
Whether he was double-teamed
Down and distance
What the season sack rate of the quarterback he was facing was
How many players rushed the passer on that play
How many of his teammates earned a pass rush win on that play
What the season pass rush win rates of his teammates were
The game's win probability
The sack expectations produced for every play can then be added up for the season, allowing us to see which players had better opportunities than others, and who beat (or fell short of) their expectations. Double-teams and pass rush wins are ESPN metrics powered by NFL Next Gen Stats data.
Let's focus on the free-agent pass-rushers and evaluate the context of their 2020 sack totals -- along with other advanced pass-rushing metrics -- to get a fuller picture of their 2020 seasons beyond the simple number of plays they brought down the quarterback. We'll also include J.J. Watt, who just signed with the Cardinals, and see whether or not Arizona got a productive player.
Leonard Floyd
2020 team: Rams | Age entering 2021 season: 28
Expected sacks: 8.6
Actual sacks: 10.5
It might seem at first glance that these are positive numbers for Floyd's 2020 season because he exceeded his expected sack number. Then again, any double-digit sack season is going to exceed expectations. The question really is whether Floyd's 10.5 sacks are more or less impressive given the expected sack information here. To that we get a pretty clear answer based on the context and numbers -- his season is less impressive than it looks.
Floyd ranked second -- behind only Pittsburgh's T.J. Watt -- in terms of expected sacks last season. No other player had the combination of quantity and quality of pass-rushing chances as Floyd.
One big factor: He recorded the fourth-most pass rushes in the league on third- and fourth-and-long, which is when sacks are the most likely to occur. Another factor is that he played beside Aaron Donald. Floyd was double-teamed at the third-lowest rate in the league, and teammates recorded pass rush wins around him at a high rate -- both of which can be at least partially attributed to Donald. Those variables lead to high sack expectation.
For comparison, free-agent pass-rusher Romeo Okwara recorded 10 sacks but those came on just 6.2 expected sacks.
Another troubling sign is that despite the lack of double-teams, Floyd ranked just 36th out of 46 edge rushers in pass rush win rate, almost exactly where he ranked the year before in Chicago (38th out of 50), when he had just three sacks.
Again, Floyd did beat his expectations and deserves credit for that. But these signs indicate that environment was a factor in his jump from 2019 to 2020, which should be a red flag for suitors in free agency.
The verdict: Buyer beware for any team judging Floyd solely on his 2020 sack total.
Trey Hendrickson
2020 team: Saints | Age entering 2021 season: 26
Expected sacks: 5.0
Actual sacks: 13.5
If you guessed that Donald led the league in sacks over expectation in 2020, you were close. He was second only to Hendrickson, whose breakout 13.5-sack campaign came despite a relative lack of opportunities.
The story with Hendrickson is straightforward because he had only 319 non-screen pass rushes. Among the other players with more than 10 sacks -- Watt, Donald, Za'Darius Smith, Haason Reddick, Myles Garrett, Leonard Williams, Stephon Tuitt and Floyd -- all but Reddick had more than 100 pass rushes than Hendrickson.
Another area to consider is that the quarterbacks Hendrickson faced didn't take many sacks. The weighted average of those quarterbacks' season sack rates was 5%, which is on the low end (the range went from about 4.5% to just over 7%).
Hendrickson, however, doesn't bring all positive signs with him into free agency: His pass rush win rate was a shade below average, though he was double-teamed at a slightly above average rate. And if we look at sacks created -- where we credit the player who first beat his blocker on a sack play rather than the player who finished it (though it can be the same person) -- Hendrickson had just 7.5, fewer than teammates Cameron Jordan and David Onyemata.
The verdict: There are some mixed signals about Hendrickson's prospects going forward, but his 13.5 sacks in 2020 are even more impressive considering the circumstances.
Bud Dupree
2020 team: Steelers | Age entering 2021 season: 27
Expected sacks: 6.8
Actual sacks: 8.0
Consider me a Dupree skeptic. Though he recorded eight sacks in 11 games before suffering a torn ACL last season, no player averaged a higher sack expectation per play than Dupree. When he was on the field, it was all set up perfectly for him.
He played in the blitz-heavy Steelers defense, and his teammates averaged 0.42 pass rush wins per pass rush, more than for any other edge rusher. The quarterbacks Dupree faced also averaged a sack rate of more than 7%, higher than for any other qualifying pass-rusher. And 17% of his pass rushes came on third- or fourth-and-long, an above-average rate.
Dupree's win rate info is also concerning. He ranked one spot ahead of Floyd -- 35th out of 46 pass-rushers. Those are two worrying signs for teams considering signing Dupree, as he failed to beat his blocker within 2.5 seconds with regularity, and though he beat his sacks expectation, his sacks and sack rate were buoyed by his opportunity and situation in Pittsburgh.
The verdict: I'm wary of Dupree's ability to produce at the same levels outside of his favorable situation with the Steelers.
Leonard Williams
2020 team: Giants | Age entering 2021 season: 27
Expected sacks: 5.9
Actual sacks: 11.5
One factor we haven't discussed is position, but it's important. Edge players are more likely to bring down a quarterback than an interior defender.
And while Williams wasn't exclusively a defensive tackle in 2020, that is where he played on the majority of his pass rushes, significantly depressing how many sacks we'd expect a player with his opportunities to accrue. Because he was the best pass-rusher on the Giants, he didn't get a lot of help from his teammates, who recorded just 0.18 pass rush wins per pass rush (less than half of what Dupree's teammates did!).
Williams' win rate was only average among defensive tackles, though he was double-teamed at an above-average rate (contributing to his lower sack expectation, too).
The verdict: The wide gap between Williams' expected sacks and actual sacks is likely a reason to be more bullish about his future.
Haason Reddick
2020 team: Cardinals | Age entering 2021 season: 26
Expected sacks: 6.5
Actual sacks: 12.5
The quality of Reddick's pass-rush chances were strong, mostly because of a high average of blitzers on his pass rushes and a high rate of third- and fourth-and-long attempts. But he recorded only 353 non-screen pass rushes, and that held down his expectation. That means that Reddick's high sack total was impressive because it overcame few chances, but his relatively high sack rate was buoyed by favorable circumstances.
His pass rush win rate was only average, and we have limited history seeing him as an edge rusher.
The verdict: Reddick's sack total underrates his production, but his sack rate overrates it. He's a riskier free-agent option because of the smaller sample, but there's upside there.
Romeo Okwara
2020 team: Lions | Age entering 2021 season: 26
Expected sacks: 6.2
Actual sacks: 10
Okwara's sack expectation was dampened by two factors:
The lack of talent around him; his teammates' average pass rush wins and overall win rates were both low.
A lack of snaps when the opponent's win probability is very low (when sacks are more likely).
On a per-pass rush basis, though, Okwara's expected sack rates were only a shade below average for an edge rusher, a bit better than I'd have expected in a Matt Patricia defense. Still, his jump up to 10 sacks is not something we'd attribute to his environment.
In 2018, he had 7.5 sacks with one of the lowest pass rush win rates in the league. He made huge gains in that department in 2020, however, finishing slightly above average, a reassuring sign for any team banking on his future.
The verdict: Okwara overcame more difficult pass-rushing circumstances than Floyd or Dupree and is a better bet going forward.
Shaq Barrett
2020 team: Buccaneers | Age entering 2021 season: 28
Expected sacks: 7.5
Actual sacks: 7.0*
Barrett's eight-sack season -- a huge drop from his 19.5-sack performance in 2019 -- looks even worse in the context of his relatively strong opportunities. That said, there are mixed signals here because Barrett did still finish in the top 10 in pass rush win rate among edge rushers for the second straight season.
It's worth noting that in 2019 he also had a very high sack expectation (9.5), though he blew that out of the water.
The verdict: His 2020 was even more disappointing given this context, but there's still reason for optimism.
*Expected sacks is only based on plays in which the player began as a pass-rusher. As a result, actual sacks when a player began in coverage were omitted (these are rare).
J.J. Watt
Signed by: Cardinals | Age entering 2021 season: 32
Expected sacks: 7.4
Actual sacks: 5.0
Let's end with the Cardinals' new signing. As a believer in Watt's ability even as he enters his age-32 season, I was little taken aback by this expected sack total. The five-sack season was a disappointment, sure, but it seemed like he would have also had a low sack expectation because he didn't have much help pass rushing, was constantly double-teamed, played against quarterbacks with low sack rates and was on a team that didn't get opponents into desperation situations much.
All that is why Watt actually did have a low sack expectation on a per-play basis. But he also had more pass rushes than any other player in 2020 and that adds up. That Watt was double-teamed as an edge rusher more often than anyone else and still posted an above-average win rate is a strong sign for his prospects going forward -- and why I'd endorse the Cardinals' signing of him. Playing alongside Chandler Jones should be mutually beneficial, as they'll both draw attention from each other.
The verdict: Expect more sack production in Arizona, but his five-sack season was a disappointment given his quantity of chances.