Of all the players on defense, Mychal Kendricks had to be the most excited when the Eagles made the switch to a 3-4 scheme.
Kendricks played behind an odd-man front in California and said he felt uncomfortable last season playing outside linebacker in a 4-3. At first the Eagles had him lining up on the strong side opposite the tight end, but that just gave the 6-foot, 240-pound rookie one more potential blocker to shed.
Realizing the mistake, the Eagles moved Kendricks to the weak side late last season and he improved. But he longed to play inside linebacker in a 3-4, especially behind a line that played a lot of two-gap football.
"I'm strong as hell, but I'd rather not have to deal with those big-[butt] blockers in my grill all the time," Kendricks said. "Every once in a while and even half a game it's all right, but when it's a whole game it's a lot on my body and it's harder to make plays.
"You take the running aspect out of my game and things can get difficult."
The premise of two-gap, 3-4 defense is simple, but executed effectively it can be difficult for offenses to beat. The Eagles aren't strictly a two-gap, 3-4 defense (think the Steelers), but they employ many of the scheme's hallmark techniques.
And mostly that involves the defensive linemen playing two gaps and taking on several blockers to free up the linebackers. Cedric Thornton and Bennie Logan are classic two-gap defensive linemen. Defensive end Fletcher Cox is more of a one-gap penetrator, but he has improved playing two gaps.
Defensive coordinator Bill Davis has done a fine job, though, of mixing up his fronts and switching off two-gap responsibilities. In many cases, it's Cox who is asked only to shoot the gap.
But Davis has schemed to match his players' skill-sets, as he has done with Kendricks, who despite his affinity for the 3-4 is not the prototypical inside linebacker for the defense.
"You know, everyone thinks the 3-4 inside backers have to be these monsters, and they really don't," Davis said. "There's different ways you can protect by simply moving techniques of your D-line. Good football players will fit into any scheme, and Mychal is a good football player."
Kendricks has had an up-and-down season, though. He got off to a good start in the opener against the Redskins but tailed off quickly and missed seven tackles in his next two games.
But Kendricks slowly regained his confidence and grew more comfortable playing alongside fellow inside linebacker DeMeco Ryans. The 3-4 may keep big offensive linemen off him more than the 4-3 did last year, but his responsibilities have grown.
"I think Kendricks has grown a lot mentally because the defense is a challenge from a mental aspect, especially inside," outside linebacker Connor Barwin said. "DeMeco's had it all along, but Kendricks continues to grow and understand what his job is."
Ryans leads the Eagles with 158 tackles, 113 of them solo, according to coaches' statistics. Kendricks is second on the team with 110 tackles, 78 solo. The coaching staffs were different, and thus the crediting of tackles was likely different, but Ryans finished 2012 with 148 tackles and Kendricks with 88.
There are many reasons for the defense's effectiveness against the run, but playing two-gap on base downs has certainly played a part. The Eagles are 15th in the NFL in run defense but 11th in yards per rush (3.95) and have allowed only seven touchdowns on the ground all season.
Ryans saluted the defensive linemen, led by Thornton, who often make stops against the run even though they have several blockers to fend off. But if they can't spring free, Ryans and Kendricks - and Barwin and Trent Cole setting the edge on the outside - have been there to clean up.
"They may not have crazy stats, but they know if they hold their blocks, me and Meco are going to be coming free," Kendricks said. "There are times when those big guys will turn around and be like, 'Yo, I've got you guys. You guys are going to be free.' "
Eagles coach Chip Kelly called the effort of the defensive line in Sunday's 34-20 win over the Lions the "key to the game." With starting running back Reggie Bush sidelined with a calf strain, Joique Bell was held to 69 yards on 23 carries. He scored a touchdown, but the Eagles stripped him twice.
It would be easy to blame Bell's day on the weather conditions, but the Eagles rushed for 399 yards.
"Those guys did a great job with just base techniques and not getting pushed off the football and had their cleats in the ground," Kelly said. They "did everything that [defensive line coach Jerry Azzinaro] teaches and allowed Mychal Kendricks to run around."
Ryans tallied 10 tackles and Kendrick picked up eight.
There are still stiff tests remaining. Even if all-pro tailback Adrian Peterson can't play Sunday when the Eagles visit the Vikings, backup Toby Gerhart is a competent backup. He averages 7.9 yards a carry.
The next week the Eagles will face the Bears' Matt Forte, and then it's the Cowboys' DeMarco Murray in the regular-season finale.