Against the Redskins on Sunday, the Eagles defense was a microcosm of last season: they played well against the run, but had no pass rush, made a backup QB look like a star (see: Cassel, Matt) thanks to a secondary that continued to give up completion after completion, and blew assignments that gave up big plays. It once again has fans and the media wondering, Brandon Boykin is the best cornerback on the Eagles, why is the team is purposely limiting his use by not playing on the outside?

Boykin had a tremendous 2013 season, finishing 2nd in the league in interceptions and garnering accolades around the league for his play despite only playing a little over half of the Eagles defensive snaps. He was the lone bright spot on a pass defense that other than interceptions was thoroughly mediocre. This year Malcolm Jenkins has joined him as a quality defensive back on the Eagles, but Cary Williams, Bradley Fletcher and Nate Allen continue to be inconsistent, average at best players. With 10 returning starters, the only way the defense can improve from last year is by the returning players improving and the play calling and game plans to improve as well.

Neither has happened.

The Eagles defense is once again a mixed bag, improving in some areas, staying the same in others, and playing worse in some. So far this season the defense is better on third downs, thanks in part to the ineptitude of the Jaguars offense in Week 1, when the Eagles forced 6 three and outs. Against the Colts and Redskins combined, they forced 4. Many underlying rate stats are still poor. In 2013 the Eagles had the worst sack percentage in the NFL at 5.2%. This year they have the second worse sack percentage, at 2.3%. They gave up 6.8 adjusted yards per attempt, 15th in the league last year, this year they are 19th, giving up 7.4. Turnovers are down significantly so far this season, from 3rd in the league last year including 8th in interceptions, to 14th in the league in total turnovers and 15th in interceptions. And after a 2013 second half that saw a run of keeping the opposition out of the endzone, the Eagles give up more touchdowns each week as they face better offenses.

The defense hasn't improved enough, so why doesn't the coaching staff play one of their best players more?

Size matters?

Chip Kelly has specific measurements he would like his players to be, though Darren Sproles is Exhibit A that this is not a hard and fast rule. For matchup purposes, Kelly wants his outside cornerbacks to be over 6 feet tall, a criteria which Boykin misses by 3 inches.

"I think our two outside corners are very good football players," Kelly said. "Again, it’s a matchup game. The bigger receivers are on the outside. The smaller receivers are on the inside. So you’ve got two longer guys in Fletch [Bradley Fletcher] and Cary [Williams] that really fit in terms of getting matched up. When most people, if they’re gonna be in '21' personnel, then they’re not small outside. They’re big outside. So when they’re big, we’re big. I think when you bring in the Wes Welkers and the great slot receivers in this league, you need to have someone that has the ability to cover them. And I think that’s what Brandon’s strength really is. That’s the way we’ve always looked at it."

In theory, this is a fine philosophy. In practice however, the Eagles don't stick with it. Nolan Carroll and Jaylen Watkins are both 5’11" (Carroll is listed at 6’1" but measured 5’11" at the Combine) and Roc Carmichael, who was the first option off the bench on the outside in 2013, is 5’10". Is a one inch difference really the reason that Boykin, a superior player to Carmichael, did not play on the outside? If so that's incredibly short sighted, no pun intended.

Practice?

The coaching staff has said they want Boykin to practice and play exclusively at the slot so that he can focus on excelling there. To his and their credit, Boykin has done just that. (From the previous link:)

"I really think, and I believe this, that one of the reasons that he’s grown like he’s grown and made the plays that he’s making is because we’ve allowed him to specialize and really focus on the nickel position and how to play," Davis said. "He’s a young player that’s still growing and I think that is one of the things that we’ve done that I’m most happy with. And I understand he’s got a lot of interceptions and second in the league, but I think that’s a product of specialization and really knowing exactly and playing a position with confidence and that’s how you win."

On one hand, having players practice and play only one position is highly efficient way to develop them at that particular role. No matter what the task, streamlining improves efficiency. But on the other hand, Boykin showed he can master two positions last season. He excelled in the slot all season long, and also established himself as an excellent gunner on punt returns, though unlike outside corner and slot corner they are not mutually exclusive positions. Still, with the high volume of practice reps the Eagles run, there is ample opportunity for him to get reps both inside and outside, which he did in training camp. The opportunity is there.

Run defense and personnel matchups

Chip Kelly wants his defenses to be be stout against the run, which is one of the reasons he prefers larger players: the bigger they are, the harder they are to block. This makes sense for the front seven, and since the Eagles play a lot of Cover 3, safeties. But for corners, especially corners in the Eagles scheme, it's a tertiary trait.

To improve the run defense, when the opposition brings out three wide receivers, Billy Davis will keep his base personnel on the field, keeping a front seven and having a safety defend the slot receiver. This gives the defense an advantage against the run by keeping a linebacker or defensive lineman on the field and bringing a safety into the box. But it gives the offense an advantage in the passing game if the safeties can't cover. Which Patrick Chung couldn't do last year, but Davis kept playing him there despite being burnt for TDs multiple times. It's one reason why the Eagles signed Malcolm Jenkins, throughout his career as a safety the Saints used Jenkins this way. But Billy Davis isn't even committed to that. Nate Allen played in the slot against 3 WR over a half a dozen times against the Redskins, not Jenkins.





From Billy Davis' Tuesday press conference:

Q. Do you think he's more important ‑‑



DAVIS: Right now we're very happy with who we have out there and the situation we have, and we're very, very pleased with Boykin, what he's doing and what he brings. I can't say enough about him. It's a starting position for us. I know it isn't to you guys, but the nickel spot is a starting position that plays in every game. They dictate what personnel group is in, what we're going to match them with.

Boykin was already being kept off the field in nickel situations last year, and the team is keeping him off even more this year. Brandon Graham, who like Boykin is not a starter and plays primarily in passing situations, has played more snaps than Boykin.

When you consider Davis' play calling, prioritizing run defense for a CB makes even less sense. Davis' base play is Cover 3, in particular Cover 3 Sky, in which a safety and three linebackers have the underneath zones and the CBs and other safety the deep zones. The deep third defenders are responsible for staying on top of the deepest receiver in their zone, which is not always the outside WR, underneath routes and run force contain are the responsibility of the linebackers and safeties. And Davis has his CBs line up 7 yards off the WR on a majority of plays, further removing them from a run play. A slot CB on the other hand is usually responsible for an underneath zone, meaning they are far more likely to be involved in a run play. Being strong against the run isn't the primary skill the Eagles value it to be, and it's not like Boykin is Asante Samuel.

Kelly wants to maximize the number of possessions he can get in a game, and a team that eats the clock up with a good running game reduces that. So having a good run defense is a nice goal. But prioritizing run defense over pass defense isn't efficient, teams are running the ball less and less every year, and passing it more and more. Unfortunately the Eagles don't seem to realize this (also from Tuesday):

Q. [Boykin] was in 52 percent of the snaps last year. He's had 32 and change this year. Is that just a product of what people are giving you?



DAVIS: Exactly, and I bet it changes as the year goes on. I bet we hit two‑ or three‑game stretches where he's got 50 percent or more. I really do believe it. It's just what's presenting us. A lot of teams are trying to come at us with a run. Right now it's 50/50 play calling against run and pass, and they're balanced, and that's not what you ever want, but part of that is because we start in a hole so often that we're behind that they get run or pass, and we've got to play both. When it becomes just a pass game then he'll be out there a lot more. When it's just a run game, he won't, just from the nature of our calls versus their calls.

That's just not true. The Eagles have faced 91 rushing attempts—which is slightly skewed as that includes kneel downs and scrambles—and 125 pass attempts, which is a 42/58 run/pass split. Last season the Eagles faced a 39/61 rushing to passing attempt split. The over-commitment to run defense is one reason why Kelly wants tall, physical corners, feeling that a 5’9" corner is not going to shed his block and defend the edge as well as as a 6’1" corner is.

"Football is a game of chess; the only difference is all 22 pieces move at once," assistant defensive backs coach Todd Lyght said. "[If] you've got Brandon Boykin on the edge, trying to stop a 300-pound lineman on a sweep play, that's tough duty. . . . "Some guys think of themselves only as cover corners. Well, if you're just a cover corner, you can't play for the Philadelphia Eagles. You have to be able to hit and cover. Asante Samuel was a great player in this organization for a long time, but he really wasn't noted for his tackling. If you can't tackle, you're not going to play for us."

That's nice, but 300 lb offensive linemen aren't sweeping out to block corners, they're blocking linebackers and safeties. They do however occasionally attempt to block players in the slot, and it was on display on Sunday. Cary Williams will be tied up on the outside not by an offensive lineman but by DeSean Jackson, who is so bad at run blocking that Jay Gruden tried to laugh it off, and Williams is unable to do anything to Alfred Morris.





Later in the game, Boykin sheds his blocker, and wraps up Morris.

Circling back to how the alignment of corners hinders their ability to defend the run, on both of those plays Williams (in the first) and Fletcher (in the second) were lined up 7 yards off Jackson. Neither were able to do anything. On another play, Boykin will read a quick screen to the outside, avoids a 300 pound offensive lineman who is trying to throw a block, and makes a tackle for no gain.





That's a good, tough physical play, the kind the Eagles pay Williams and Fletcher to make but weren't on Sunday. Meanwhile Bradley Fletcher was giving up big gains downfield, and with an opportunity to play physical, gave up a TD on a slant route.





And when playing off may have been the better option, Fletcher pressed and was beat for a big gain.





Fletcher had his worst day as an Eagle on Sunday, but the Eagles kept him on the field for every play for the first time this season. Against Jacksonville, Fletcher only played 85% of snaps, Nolan Carroll substituted in for him. Against Indianapolis he was taken out for two plays. But on Sunday, when he was very clearly struggling, he was never taken off the field, even for a single play. Meanwhile, Boykin continued to make plays when given the chance.





Boykin will be responsible for the inside receiver on this play, and when he sees that the throw is to the short outside route, he immediately reads it and is the only defender in position to make a tackle. Nate Allen gets turned around and Bradley Fletcher is blocked. If not for Boykin, this would be a first down.

Boykin is at his best in the slot, where he can be more involved in the action as an underneath defender in zone. But in base defense, the Eagles are wasting him on the sideline while the starters struggle or Nate Allen covers wide receivers. Cary Williams and Bradley Fletcher may be more ideal corners for Chip Kelly on paper, but on the field where it matters, they're not getting the job done on a consistent basis, and Boykin continues to play well when given the chance. But he doesn't get enough chances, because Billy Davis isn't putting his best players in their best position to succeed. The height disadvantage the Eagles are so concerned about doesn't matter when the starters—who are only 6'0" (Fletcher) and 6'1" (Williams), they're not Richard Sherman or Brandon Browner sized—are getting beat, and when the first option off the bench has been inferior players who are only an inch or two taller than Boykin. Boykin doesn't need to play every snap, but he should be playing more than the 32% of plays that he has so far, especially when the starters are struggling like they did on Sunday.