Analytics of Defensive Injuries

A couple weeks ago I published a post addressing how different teams adjusted to the losses of players on their offenses due to injury. While there are no individuals as valuable to the defense as a quarterback is to the offense, losing a defensive player can still result in massive changes to a team’s schemes. Defenses with elite players often design every set they have with the assumption that this player will be able to do something extraordinary. They isolate corners on the opposing team’s best receiver, they trust that front seven players can either draw a double team or beat a single blocker, they assume that a safety can cover the field from sideline to sideline. When they lose these players, they know the backups aren’t capable of these same elite plays. They are forced to adjust everything about how their defense plays and aligns.

Teams react differently based on where the loss has occurred on their defense. I’ll start by talking about the Bengal’s loss of Geno Atkins, probably the best defensive tackle in the NFL. After that I’ll address how the Bills handled the multiple losses in their secondary at the beginning of the season. I’ll end with the Broncos and Von Miller, who missed six games due to a suspension to start the season.

Cincinnati Bengals

Losses: Geno Atkins

Of all the great players to go down to injuries this season, Atkins, Rob Gronkowski, and Aaron Rodgers are the only three reasonably able to call themselves the best in the league at their positions. Atkins has slid under the radar some due to playing an underappreciated position on an underappreciated defense. But last year he had double digit sacks from the defensive tackle position, and he was on pace to repeat that performance this season before his injury. He is the best interior pass rusher and one of the five best defensive players in the NFL.

With everything I said above, you can imagine that losing him would greatly affect the way the Bengals play defense and the way teams attack them. The obvious changes have definitely occurred. Teams see less need to double Atkins’s replacement, freeing linemen to block the defensive ends coming around the edges. The Bengals have compensated by mixing up their pass rush schemes, bringing linebackers on inside blitzes more often and occasionally dropping defensive linemen into coverage. With Atkins they were content to present clear, uncomplicated fronts and trust their players to beat the opposition. Now they are doing more to cover their schemes in order to try to confuse the offense.

While Atkins is at his best as a pass rusher, the more significant changes have come in the running game. Offenses facing the Bengals are now able to be more balanced in the ways they attack on the ground. Atkins always lined up on the outside shoulder of the strong side guard (a 3 technique for those of you familiar with the terminology) and offenses generally tried to avoid running towards him. This forced teams into a lot of weak side runs that the Bengals linebackers could flow to without worrying about congestion. Now that Atkins is out, teams are able to attack with a more balanced scheme. Before the injury the Bengals played a great deal of two deep coverages with a mixture of man and zone underneath. They were happy to keep six men in the box even against two back sets. The injury to Atkins has forced them to drop a safety into the box, leaving them in single deep coverage with more man underneath. They’ve handled this change well due to the impressive talent on their defense, but the loss of Atkins has left them exposed to more big plays in the passing game.

Buffalo Bills

Losses: Jairus Byrd, Stephon Gilmore, Ron Brooks

Unlike most of the teams I’ve covered, the Bills are perfectly healthy right now. The injuries to their secondary came early in the year, but everyone returned by the second half of the season. The most notable loss was Pro Bowl safety Jairus Byrd, one of the best cover safeties in the league. They also lost last year’s first round pick Stephon Gilmore and his backup Ron Brooks for several games during the same timespan.

The Bills’ scheme is designed to put tremendous responsibility on everyone in their defensive backfield. Unlike many teams who use their safeties to prevent big plays, the Bills ask theirs to create them. They play a lot of Cover-2 Man with the safeties stationed only about fifteen yards off the line of scrimmage, lurking to cut underneath post or seam routes. This puts even more responsibility on the cornerbacks not to let their man get separation. The injuries made them back off slightly, but not as much as you would expect. They still played a great deal of press man, and their replacement for Byrd wasn’t any less aggressive in going for interceptions. The Bills trusted their backups, and that trust wasn't always rewarded. They were exposed regularly in the pass game until they were able to bring their starters back.

The Bills have done more to disguise their schemes since their starters returned, bringing Byrd up into the box presnap and trusting his speed to get him back into position. They have also asked their linebackers to be more aggressive, particularly Kiko Alonso. A rookie second round pick, Alonso is a fast but undersized linebacker who is at his best in pass coverage. Early in the season they relied on him a great deal in coverage, and he was often hesitant to react upwards to a run set. He made plenty of tackles, but they were usually four or five yards downfield. Since the return of the injured players, the coaches have begun trusting their coverage and have encouraged Alonso to react forward. His tackles now come nearer to the line of scrimmage or in the backfield. Part of this is due to the natural progression of him as a player, but there is no way to miss the uptick in the aggression of his play since the return of the injured players in the secondary.

Denver Broncos

Losses: Von Miller

Injuries are not the only thing that can remove a player from a team’s lineup. Von Miller, one of the best pass rushers (and overall defenders) in the NFL, missed the first six games of the season due to a substance abuse violation and the subsequent cover-up attempt. The Broncos’ ability to respond to this loss was further hindered by the offseason departure of Elvis Dumervil due to a bizarre paperwork issue. They attempted to replace these losses with free agent signing Shaun Phillips and the less than competent rotation of Robert Ayers and Nate Irving.

As with Geno Atkins in Cincinnati, the presence of Miller in Denver limits the options available to opponents in the running game. Unlike with Atkins, these teams choose to attack Miller when he is in the lineup rather than run away from him. Miller is anything but a liability in the running game, but his strength is as a backside pursuer, using his athleticism to chase down runners from behind. He isn’t a run stuffer capable of using his bulk against a lineman attempting to push him backwards. This isn't a problem for the Broncos, however. The one dimensionality forced on opposing offenses allows them to move stronger run defenders like Derek Wolfe and Terence Knighton into position to make plays.

The return of Miller has allowed the Broncos to make drastic changes to their defensive scheme. The improvement in their pass rush has allowed them to play almost exclusively man coverage without fear of the quarterback having time to break it down. But more significantly, Miller’s versatility has led them to completely reshape the alignment and scheme of their front seven. Without him they played a very vanilla 4-3 scheme and rarely blitzed their linebackers. With his return they now offer much more varied looks, most commonly lining up in a 3-4 scheme. The differences between the two systems are often overstated, but this alignment gives them a significant advantage in their pass rush. Shaun Phillips is still listed as a defensive end, but he now primarily plays from a two point linebacker stance, allowing him to drop back into coverage when they don’t feel they need his pass rushing ability. They rarely bring both of their edge rushers, but offenses are forced to guess which is coming, and when they guess wrong they find themselves exposed to a suddenly dangerous pass rush.