How much does EDGE depth matter to the Eagles?

We first should ask ourselves: “How often is EDGE4 on the field for Philly?” Fortunately, that’s a pretty routine question.

Jim Schwartz has been the defensive coordinator in Philadelphia for three years, and has prioritized the pass rush since he arrived. We can look at the Eagles EDGE snap counts over those three seasons (chronologically ordered, 2016 - 2018) to see just how often EDGE4 impacts the game.

I used snaps/game, instead of pure snap counts over the course of a season, to control for injury — specifically, the Derek Barnett injury in 2018, which left the Eagles with basically three EDGEs for the remainder of the season. But more on that later.

We can see that, over the past three seasons, EDGE3 has steadily climbed in usage — without much sacrificing of EDGE1 or EDGE2 snaps, either. This can be explained by the 3DE sets that Jim Schwartz has increasingly employed during his time in Philadelphia. On long and late downs, Schwartz might bench one of his defensive tackles to line up Brandon Graham or Michael Bennett on the inside and get his best four rushers on the field.

Now, we do have to be careful with our number for 2018, which is shockingly high: 38.25 snaps/game for Chris Long, just underneath Derek Barnett’s 39 snaps/game. Long may have been the season EDGE4, but once Derek Barnett officially went on IR before Week 8, he became the EDGE3, and his numbers accordingly ballooned.

We can see the effect of the Derek Barnett injury on this chart, which breaks down the Eagles’ EDGE4 snaps/game for the 2018 season, by individual game — it may have been Chris Long one week, Derek Barnett another week, and Josh Sweat a third week.

It isn’t hard to see when Derek Barnett went on IR, and how that affected the snaps of EDGE4 — it’s even easier still to find the one game before Barnett went on IR that he was inactive for.

It’s a tale of two halves here. On average, the EDGE4 took 48.74% of the snaps in the six games Derek Barnett was active and 10.91% of the snaps when Barnett was inactive, for a season-long average of 23.53%.

It would seem that, once Derek Barnett went down, Jim Schwartz didn’t feel that he had an EDGE4. Yes, at least 4 EDGEs played in 11 of the 12 games without Barnett — but only once did that player take more than 20% of the snaps on defense. In other words, that EDGE4 — namely, Josh Sweat — wasn’t so much a player Schwartz wanted to get on the field, as he was a placeholder in dire circumstances on long, tiring drives.

When Schwartz did have Barnett healthy, it seems that Philadelphia was willing to deploy as true of a four-man rotation at EDGE as we’ve seen in the league: again, with Barnett healthy, the EDGE4 averaged almost 50% of the snaps/game.

Looking at only those first six games in which Barnett was active, the Eagles’ DE snap counts looked like this:

This is a blistering pace of EDGE4 play — over half of the snaps! It’s highly unlikely that any other team was getting this much play out of their EDGE4 — which is as we should expect, as no other team in the league had four EDGEs as talented as Philly did.

The reality of the Eagles’ 2018 season with Derek Barnett active is that their EDGEs were essentially interchangeable. Each of the four had the fewest snaps/game in one of the six weeks in which all were active. There was no EDGE4 — there were just the four EDGEs.

Incidentally: if there was an EDGE4 during this time, it was Chris Long, as we can see above. Of course, Long retired this offseason, citing the expectation that his role in Philadelphia in 2019 wasn’t going to be as significant as he wanted it to be. While the EDGEs were relatively comparable in playing time across this small sample size, it may have alluded to things to come, from Long’s perspective.

Could we reasonably have expected these percentages to remain consistent across the course of a season? It’s difficult to say — but if we compare 2017’s EDGE4 snaps with 2018’s EDGE4 snaps, we see that Philadelphia’s rotation remains deep when everyone is healthy — even into the playoffs.

The outlier data here (Weeks 15 and 16) are actually Wk 16 (v. OAK) and the divisional round of the playoffs (v. ATL). In both games, Barnett saw markedly fewer snaps than usual — but let’s not forget, Barnett did have surgery for a sports hernia in the offseason, so there’s a chance they were just managing his reps.

We do have to wonder: why bother going out and acquiring the necessary players to be 4-deep at EDGE? Why construct your team such that your fourth EDGE is taking over 40% of the snaps in the Super Bowl? What is the value of this approach?

Anecdotally, we say that a strong EDGE4 — generally, strong EDGE depth — ensures the freshness of your pass rushers relative to the opponent’s offensive tackles, as we get later in the season.

If there’s data that exists to prove/disprove that claim, I don’t have access to it. I couldn’t find pressure rates on a game-to-game basis. If we simply look at QB hits/game by week over the past three seasons for the Eagles (EDGE players exclusively), we don’t see a significant trend or increase in pass rush efficacy as the season progresses.

That said, the freshness argument makes sense from a heuristic perspective: the less snaps your starters play, the less worn down they should be by the final weeks of the seasons, and the more effective they should be.

Of course, if Philadelphia doesn’t change how they distribute their EDGE snaps later in the season — and it would seem that if they do, it’s only slightly — then you’re still playing the “starters’ and “depth guys” to the same proportions, and you’re not really reaping the benefits of fresher starters.

The other benefit of EDGE depth is the more traditional benefit: protection from injury. With a deep pool of EDGE rushers, the Eagles shouldn’t lose pass rush efficacy on the team level in the event of an injury. They have enough rushers to stay dangerous.

Again, it’s very difficult to break pressure data into in/out splits of injury timeframes, but anecdotally, this makes sense. The trio of Long, Bennett, and Graham didn’t magically get better without Derek Barnett on the field. With him, they averaged a sack every 102 pass-rush snaps and a QB hit every 21 pass-rush snaps; without him, it was a sack every 65 pass-rush snaps and a QBH every 25 (data via PFR and PFF).

Yes, the sack numbers were better — but sacks are heavily situational. The QBH numbers actually got worse. Of course, we’re only looking at defense ends here — but we don’t have a strong signal that when Barnett went down, the Eagles’ healthy EDGEs benefitted from the increase of playing time by churning out more production. They weren’t more effective than Barnett was, when he was healthy: in 2018, Barnett was churning out a sack every 68 snaps and a QBH every 15 pass-rush snaps.

It shouldn’t be a shocking claim: the team got worse when Derek Barnett went down. Barnett’s a good player, and losing a good player always hurts. Critically, however, it’s not like Barnett’s snaps were replaced — that is to say, Josh Sweat didn’t step up into Barnett’s role. Rather, those snaps were assumed by the preexisting rotation. The four horsemen off the EDGE became the three horsemen.

This season, Philly looks to be only three horsemen deep once again: with Bennett shipped off to New England and Long kickin’ his feet up on a lawn chair (probably climbing another mountain, if we’re being honest), the Eagles EDGE room boasts of Graham, Barnett, and 2018 cast-off Vinny Curry.

Now, last time Curry was here, he took 56% of the snaps — he can be a part of that four-deep group that Schwartz foreshadowed in 2018. But beyond him, Philadelphia has Sweat, rookie Shareef Miller, Daeshon Hall, and practice squad hero Joe Ostman.

Slim pickin’s.

If they want to go for a four-man rotation at EDGE once again — which they seemingly do — then someone needs to step into ~50% of the snaps. That’s not for the faint of heart; that’s no “role player.” That’s nearly a starter.

The leader in the clubhouse is seemingly Josh Sweat, but let’s not forget: Sweat was EDGE4 for six consecutive weeks (Wk 8 - 14) last offseason and could barely break 20% of the snaps. In 2018, he wasn’t ready for 50% of the snaps — and most fourth-round rookies aren’t, so that’s okay.

But most fourth-round sophomores aren’t ready for 50% of the snaps in Year 2, either.

On top of that, Josh Sweat is a medical red flag. He was unable to stay healthy during his first NFL year and had his practice time closely monitored at Florida State given his history of knee issues. If Sweat goes down — which is more likely than the average player going down — the Eagles are barren behind him.

From a production standpoint, it’s hard to nail down just how much EDGE4 matters to the Eagles defense — the data just isn’t there for us to sink our teeth into. But we know it matters in and of the fact that it takes a healthy amount of the snaps: 50% at its peak, closer to 30% at its floor. Jim Schwartz wants a stable of rushers to tap into, and until someone proves otherwise in camp, he doesn’t have that right now.

We may look to 2016, Schwartz’s first year as DC, as a model for 2019’s snap counts. The first table shows us what it looks like: Brandon Graham (75%) and Connor Barwin (70%) were the starters, while EDGE3 (Curry) clocked in at 42% and EDGE4 (Marcus Smith, of all people) hit 21%.

Considering the extension Philadelphia gave Graham, it’s clear they still view him as a starter and should be willing to play him that heavily — and considering the lofty draft investment in Barnett, he also should be able to shoulder that load (if healthy). But that distribution isn’t how Schwartz has seemingly molded this roster over the last few seasons, and it will be interesting to see if Philadelphia’s strong pass-rush — which took a step back in 2018 — returns with a new distribution of snaps.