How important is an elite pass rush?

Football is a sport where old habits die hard, and where old ideas tend to stick around - either through inertia, intellectual laziness, or both - a lot longer than they should. The best in the business are generally those ahead of the curve, rather than those running old trends into the ground.

“The problem is never how to get new, innovative thoughts into your mind, but how to get the old ones out.” - Dee Hock

Part of the NFL’s current conventional wisdom is that the pass rush is the most important element of the defensive side of the game. And, at this point, pass rushers are given a spot in the position hierarchy below just the quarterback - and they have the salaries to prove it.

Photo by Dustin Bradford/Getty Images

But, is the conventional wisdom right? Are pass rushing, and pressure on the quarterback, the most important driver of defensive success in the NFL? The NFL, like any athletic competition, is an arms race, and in arms races - and outbreaks, incidentally - survivors adapt.

As rule changes in the league gave primacy to the passing game, successful teams changed their offensive strategies to incorporate more passing, with the importance of the running game continually falling off since the late-1970s.

In response, defenses looked for ways to put more pressure on quarterbacks, to try to reduce the effectiveness of the passing game, and the era of the pass rushing superstar ignited. Which, in turn, triggered a corresponding explosion in the size of offensive linemen, given the solemn duty of protecting their quarterback from these tightly wound predators.

Photo credit should read MARK D. PHILLIPS/AFP via Getty Images

The ascendance of the passing game has grown at an even greater clip over the course of the past decade, with quick release passes, aimed to beat even the fastest rushers, becoming a critical piece of the modern game. Even with these offensive adaptations, in the minds of many, defensive pressure is still king.

However, ‘conventional wisdom’ is always worth a re-examination, and we live in a time of unprecedented access to data about all sorts of things - including sports performance - and several analysts have taken it upon themselves to do a deeper investigation into what aspects of NFL defenses are most responsible for their overall success.

Pass Rush and Coverage, Explored

In early 2019, Pro Football Focus writers Eric Eager and George Chahrouri conducted a study where they examined defensive success as a function of pass rush and coverage competence. Their work is quite detailed, and well worth a read if you’re into that sort of statistical analysis, but I suspect their conclusions will be of greater interest to most of the readers here. They include the following insights:

• Coverage (as defined by PFF) better predicts defensive success than pass rush (as defined by PFF), but it is harder to maintain, both individually, and at the team level from year to year.
• It is difficult to have a successful defense based on pass rush alone, without a defense that can cover.
• Pass rush pressure does affect offenses negatively, and it tends to be more stable from year to year than good coverage.
• Coverage success is more dependent upon the performance of a unit, than the performance of an individual, like a pass rush can be.
• The nature of coverage means that you should have broad competence and depth across the defensive backfield. [PFF’s 2019 top secondaries can be found here.]

But Which Is More Important?

The PFF authors revisited their work a few months later, this time to look at whether coverage or pass rush was more important to dictating the QB’s time to throw in the pocket, which, unsurprisingly, is incredibly important for determining whether pressure occurred on a play. They found that their coverage scores correlated positively with longer time in the pocket - good - and that their pass rush scores correlated with shorter time in the pocket - also good. But they also found that while the shorter time in the pocket caused by pass rushes caused QBs to throw faster, even fast, short throws can lead to play success. Accordingly, their conclusion was that the role of coverage in reducing play success was “much higher” than that of a pass rush.

So Why Are Pass Rushers Paid More than DBs?

If the pass rush is less important, all things considered, to defensive effectiveness than coverage, why isn’t that signal being picked up in the market? Why are the best pass rushers paid nearly 50% more than the best cornerbacks?

“At the player level, pass rushers with more than 400 snaps in consecutive seasons have pass-rush grades that correlate at a rate of roughly 0.62 (r-squared 0.38) for both per-snap and the aggregate level. On the other hand, coverage players with 400 snaps in consecutive seasons have coverage grades that correlate at a rate of roughly 0.34 (0.12) for both per-snap and the aggregate level.” [PFF]

What that translates to is, it’s easier - at the individual player level - to identify consistent, top performers among pass rushers than it is to do so among cornerbacks, and to reward them accordingly. “Coverage” is generally the product of a matrix of players, whereas “pass rush” is more player specific. That doesn’t mean that pass rushers are more important than cornerbacks, it just means their performance is less confounded by the play of others, and thus easier to more directly reward.

But Wait There’s More

Another 2019 study, this time by analysts at ESPN, looked at the importance of pass blocking versus pass rushing, utilizing 2.5 seconds as the threshold for either pass blocking success or failure. Using the “pass block win rate” (PBWR) and “pass rush win rate” (PRWR) metrics they had developed from NFL NextGen Stats, derived via player tracking data, they looked at the winning percentages for teams that excelled in each.

During the period studied (2016-2018), what they found was that teams with the better PBWR won 60% of their games, whereas teams with the better PRWR only won 52% of their games. In 2018, for instance, none of the bottom 12 PBWR teams made the playoffs (8 of the top 12 PBWR teams did), but the Patriots, with a bottom 5 PRWR, ended up winning the Super Bowl. Additional data is presented, but their conclusion is concise: “it’s more important to have the best offensive line in the NFL than it is to have the best defensive line.” An accompanying corollary was that it’s important to invest in the offensive line as a group, and it’s better to avoid having a particularly weak blocker than it is to strive for having an elite one. If you’re sensing a pattern at this point, you’re not alone.

Looking at the 2019 data, 3 of the top 12 PRWR made the playoffs (4 of the bottom 12 did), while 5 of the top 12 PBWR made the playoffs (4 of the bottom 12 did).

What Does this Mean for the Redskins?

At this point, the broad expectation is that the Redskins will select EDGE rusher Chase Young with the number 2 pick in the draft. He’s considered by many to be the best player available, and his talent is undeniable. He would absolutely bolster a defensive line - that while stacked with high draft picks - has struggled to be effective (in 2019, the Redskins had the 25th PRWR in the league).

But, the team has significant problems elsewhere. Its PBWR was tied for 17th in the league, with only Chase Roullier among the top 10 at his position. Starting left guard Ereck Flowers is now in Miami and the left tackle position is very much up in the air. The Redskins team coverage grade was 23rd in the league, bolstered only by Quinton Dunbar, who is now in Seattle.

With significant holes across the roster, including in perhaps the team’s two most important position groups, it makes tremendous sense for the Redskins to optimize their number of picks in the upcoming draft and increase their talent level across the board, rather than invest an incredible amount of draft capital in a position that, ultimately, has less actual, than perceived, impact on the outcome of games.