There has been plenty of attention paid to the transition that Trent Cole and Brandon Graham will make as the Eagles move from a 4-3 defense to a 3-4 this season. Little has been made of perhaps the most talented player on that side of the ball and the change he will encounter.

Fletcher Cox had a very good rookie season. The Eagles' top pick in 2012 lived up to his billing as the 12th overall selection in the draft, recorded 5 1/2 sacks, and had "budding star" stamped on his helmet heading into his second year.

If Cox could have that kind of first season when the defensive coordinator and his defensive line coach were fired in midseason, what could he do with a new staff working with a clean slate? The possibilities for the defensive linemen seemed endless.

Even when Chip Kelly hired Bill Davis as defensive coordinator and it became clear that they would switch to a 3-4, there was the belief that they would find a way to utilize Cox's inside pass-rushing skills. Davis ran a 4-3 "under" scheme in Arizona, in which one defensive end could play one gap while the other end took on blockers and was responsible for two gaps.

Surely, Davis would play to Cox's strengths as a playmaker and line him up as a three-technique end (opposite the outside shoulder of the guard), the thinking went.

The Houston Texans ran a similar scheme to cater to defensive end J.J. Watt's skill set as an explosive pass rusher. Few players are in Watt's class, including Cox, but the argument could be made that the Eagles should build their defense around their most gifted player.

"To one guy? No, we don't cater our defense to one guy, because there are 10 other guys you have to worry about," Kelly said Tuesday. "There are a lot of different things when you go through everything. We're going to try to play to the overall team strength: What are we best at?"

Kelly and Davis are still in the searching phase. They may be stuck there all season, if the first preseason game was any indication. The coaches are not certain that the Eagles can transition to a two-gap, 3-4 alignment this season. Much of what the team displayed up front in the preseason opener against the Patriots was a basic 3-4 defense.

That meant Cox played mostly as a five-technique end, lining up over the offensive tackle. He looked like he was a rookie again. He exploded off the ball when he needed to take on blockers. He didn't clog lanes when he was double-teamed. But he didn't seem comfortable the few times he was singled up against tackles.

On the opening play from scrimmage, he was flattened by tackle Nate Solder as Patriots running back Stevan Ridley bolted through his gap and ran 62 yards.

Cox has never looked so lost. When the Eagles drafted him out of Mississippi State, they touted his pass-rushing abilities, said he was versatile enough to play as a 4-3 end, and believed he would flourish under defensive line coach Jim Washburn.

Asked about Washburn, who lost his job last season, and how he let his linemen run wild after quarterbacks, Cox smiled.

"We could just be quick off the ball," he said. But the pass rush-first mentality created other problems behind the front four.

Cox conceded Tuesday that he was frustrated. He said that phone conversations he has had with former teammate and mentor Cullen Jenkins, who signed with the New York Giants in the offseason, have helped his state of mind.

"He keeps telling me that I just need to be more patient," Cox said. "I need to do more read and react rather than trying to get off the ball as fast as I can."

Cox said that he isn't just playing two-gap football. There were times against the Patriots when the Eagles had four down linemen and the defensive ends had only one-gap responsibility. But Cox will need to do both if he's going to play all three downs.

"I know as an offensive coach, I would love to know when that guy's in the game, it's two-gap defense; when that guy's in the game, it's one-gap defense," Kelly said. "They've got to be able to play at both."

Still, Davis has said that he isn't going to beat his 3-4 into a round hole if the personnel proves to be square. He's going to suit the scheme to the talent. But as he has stressed, perhaps more than any other Eagles coach including Kelly, there is going to be a learning curve.

Cox said he believes the new system will make him a complete lineman, even if his sack numbers decrease.

"It'll take me a little longer to pass-rush," Cox said, "but there will be opportunities on third downs."

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