The Eagles entered the offseason with a clear top priority: add speed at wide receiver. You could even say that their overall priority was speed (and health, and love of the game), and that their biggest position of need was wide receiver, as they added explosive movers everywhere, but spent the most resources by far at wide receiver.
It’s easy to get excited about these acquisitions — and both fans and the team should do so. The wide receiver room is inevitably going to be better than it was last season, and the offense at large should generate more chunk plays, cutting down on those laborious scoring drives that were knocked off course with one minor error from last season
But the Eagles weren’t an explosive receiver or two away from winning it all last year. They gave up deep touchdowns at twice the rate of other NFL defenses, allowed massive scoring runs in the first half, and were the worst team in the league at covering outside receivers. The defense had its stretches of solid play, but was inopportune and generally untrustworthy.
The Eagles have historically won with their front four under Jim Schwartz, and in his four-year tenure, have poured resources onto the defensive line while scraping by in the defensive backfield. This year, they traded for and extended CB Darius Slay, a long overdue move that secures the best cornerback that has ever played under Schwartz. On the surface, this is the move the Eagles can point to and say: “Yes, we prioritized speed at wide receiver — but look! We fixed the secondary as well!”
They did not. No subsequent moves were made at the other outside cornerback position, with Avonte Maddox, Sidney Jones, and Rasul Douglas figuring to once again enter a messy camp battle of middling options to define a Week 1 starter to get roasted opposite Slay. The Eagles have lost quality coverage linebackers in the last offseasons in Jordan Hicks and Kamu Grugier-Hill and replaced them only with UDFA T.J. Edwards and raw rookie third-rounder Davion Taylor. And, in perhaps the single most important loss of the Eagles’ five years of free agency under Doug Pederson, safety Malcolm Jenkins was cut.
To replace Jenkins, the Eagles have taken a shotgun approach. In free agency, they added Will Parks, a depth safety from the Broncos who has experience covering over the slot and playing in the box. In the draft, they took Clemson box/slot hybrid K’Von Wallace in the fourth round. And internally, they moved Jalen Mills from cornerback to safety, tagging Mills as the titular starter for the role as they enter training camp.
What exactly is the box safety role? When Jenkins played it, he saw the majority of his reps come from a linebacker alignment, while he had a near-even split between slot corner and deep safety reps in other shells. But snaps don’t matter as much as responsibilities do: Jenkins was frequently tasked with underneath zone coverages that required reading multiple route stems, relating to multiple receivers throughout the concept, and reacting quickly to conflicting run/pass keys.
Jenkins, an ex-cornerback converted to safety, enjoyed natural coverage ability that allowed him to win from this alignment against tight ends, slot receivers, and running backs. But that isn’t what made Jenkins special here. There are a lot of safeties who can cover your average tight end or running back; there are few safeties with the instincts and play recognition of Jenkins, and his high-impact plays remained even into his 30s as his athleticism depreciated as a result of his mind for the game.
BANANAS play from Jenkins as hole defender in Inverted Cover 2. Zone spacing and awareness out of this world— Benjamin Solak (@BenjaminSolak) December 11, 2019
*Moves with Eli's eyes, but continues to gain depth
*Anticipates throwing motion, sees outside route break outside
*Flips hips, gains depth, athleticism to finish
The position that Jenkins played for Philadelphia is mentally taxing. On any given play, the box safety is going to have more complex run fill responsibilities than an outside corner, and is likely to have a wider variety of responsibilities in the passing game conditional on route distribution and releases. In many match coverages, players like Jenkins, who are responsible for hook zones or overhang fills, are actually relating to and reading routes, while outside corners are locked in man coverage on outside receivers.
Can Mills handle this much mental responsibility? Does he have the pre-snap recognition and quick processing necessary to stay sound against RPOs that target him, or the field vision to feel common route concepts and sink underneath routes behind him? We don’t know the answer for certain, as Mills is just now transitioning to this role. But last season, Mills played some box snaps for the Eagles in Week 11 against the New England Patriots. Here’s what he said about that game, in relation to his new role:
I had fun that game. I was around the ball almost every play. I think the biggest thing for me is always wanting to be around the ball, whether it’s getting a pass breakup, getting a chance to pick the ball off or make a tackle, blitz. I think that’s the biggest thing, trying to be a tone-setter and a game-changer.
If we highlight that game as a benchmark for what Mills could do in his new role, one thing jumps off the film fairly quickly: the Eagles played as much man coverage as they had in any game during the 2019 season. This makes sense: the Patriots’ receiving corps wasn’t that good, so they could hang with them one-on-one in theory (in practice, they still struggled). Mills was regularly tasked with covering Julian Edelman in the slot, which put the Eagles’ CB1 against the Patriots WR1. Again, makes sense.
But it also served to protect Mills from the necessary coverage checks he’d have to make in zone coverage. And despite that protection, he still struggled. Here, watch Mills successfully “Banjo” or “Buddy” a two-receiver stack with Rasul Douglas by playing with inside leverage and playing the first in-breaking route from either of the two receivers, while Douglas plays the first out-breaking route. Mills was only able to do this after failing it earlier in the game, where he missed a similar call from Ronald Darby following motion to a two-receiver stack, leading to an easy completion and YAC play.
Mills knows this check from his time playing corner — but when you’re dealing with motion, changing pass strengths, empty backfields, and a slew of other responsibilities as a potential run fill defender, mental mistakes find their way through the crack a little easier.
You can see Mills freeze up on clear run keys multiple times against the Patriots as well, arriving late to the contact point and allowing big rushing lanes to open in his prescribed gap.
One thing that Mills is certainly unaccustomed to is reading offensive line action to decipher run/pass quickly. Here, Mills respects the threat of a quick pass despite the offensive line’s aggressive run-blocking action, and the fact that both potential receiving threats are occupied by other defenders in the event of an RPO or quick pass. On both plays, other secondary players further away from the play are able to more quickly identify and play into the run, despite Mills having the keys right in front of him.
Run defense was predictably a steep learning curve for Mills in this one game of box play, and will remain so as he fully transitions from corner to safety. As he said on his newfound run responsibilities:
“It’s a lot different run fits that you have to know about. It’s a lot of stunts that the D-line does, so anything can change at any given moment. … I may have the C gap on one play, the guard may pull or a tight end may swap over and I’m in the A gap or I’m in the B gap.”
If the New England film was meant to be a preamble of Mills in Jenkins’ role, then it was truly the smallest foretaste possible. Mills played with kid gloves on, and that’s not his fault, nor should it be held it against him. But Mills was essentially a slot corner instead of an outside corner in that game — not the true chess piece and problem solver that Jenkins has been for so many years.
The most concerning part? Mills wasn’t even that good of a slot corner in the game! His stats were solid, but the film reveals what it often does with Mills — that he gives up consistent downfield separation to even above-average athletes, and does not have the technical mastery to conceal his physical limitations.
Some will like that second play in coverage — I don’t. Mills does well to not bite on the fake to the post, which leaves him in position to play the corner, but Mills turns his head far too early, allowing Edelman to maintain and widen his downfield stack. Were this ball accurate, Mills wouldn’t have had a play on it given his modest vertical burst. Meanwhile, the ball is inaccurate, and still is nearly caught, because Mills opens his hips and backpedals blindly into the catchpoint like an outfield confounded by the sun. This is a good result but bad process, and similar plays would not often yield PBUs.
Mills’ best plays against the Patriots came when he was tagging RBs in the flats or carrying tight ends downfield, which is to say that Mills didn’t play better in the box than he did out wide — he just covered worse receivers from the box than he did out wide.
Little, if anything, is reminiscent about Malcolm Jenkins’ game in Jalen Mills’ Week 11 performance. To expect it to be so, or to expect Mills to become Jenkins this year, is unfair. However, from a wider view, the Eagles have waved their hand over that critical and complex box safety role, implying that the combined efforts of Mills and Parks and Wallace will account for Jenkins’ loss. This is not dissimilar to their approach to the third safety spot over the last few seasons, as they always claimed that a trustworthy veteran like Corey Graham or Andrew Sendejo would get the job done, and that trustworthy veteran invariably proved a liability. It is just a more dire bet, as it’s now on a starting job, not a subpackage role.
The Eagles don’t have a Malcolm Jenkins on the roster, but they knew that and we knew that. What they also don’t have on the roster is a starting-caliber box safety. They have a few players who might become that, but all three are far from a sure bet, and the leader in the clubhouse is only there because he couldn’t hack it at outside corner, no matter how hard the Eagles tried to convince us he could. If Mills truly is the man for the job, the Eagles’ defense will be stunned to discover that he can be picked on just as easily, if not easier, in his new role than he was in his old one.