Brandon Graham's locker is next to Fletcher Cox's locker. Cox said the two never discuss the link that defines the way both are viewed in Philadelphia, as former first-round picks so coveted that the Eagles traded up in the draft to get them.

But it's an inescapable label. And it's one both have lived up to in recent games.

A defensive end, Graham was the No. 13 overall selection in 2010. Cox, a defensive tackle, went 12th in 2012. They are the two highest picks the Eagles have made since 2000. Their performances during the last month have been among the few bright spots in what is expected to be coach Andy Reid's final season, and they will need to be building blocks for the next coach's defense.

"It's big for us to make sure we keep stepping up," the 24-year-old Graham said. "We're going to have a young D-line next year. And Trent Cole's going to be here, someone I always looked up to. And whoever else they have on the D-line with us."

Cox and Graham are locks to be on the roster next year. Cole, who is guaranteed $5.1 million next season, will be on the roster, too. So will second-round pick Vinny Curry. Defensive tackle Cedric Thornton, who is in his second year with the team, also has an intriguing future. But there is much uncertainty elsewhere - especially with Darryl Tapp, Cullen Jenkins, Mike Patterson, and Derek Landri.

That's why the development of Cox and Graham remains so important for the Eagles. They need to be front-line performers to justify the team's investment, but it's still too soon to anoint either of them. There is reason for encouragement.

The two lead the Eagles in sacks with 51/2 each. (Jason Babin, who was cut Nov. 27, also had 51/2 with the Eagles.) Their most impressive game was Thursday night against the Cincinnati Bengals, when Graham finished with 21/2 sacks and Cox recorded 11/2. They were regulars in the backfield, pestering Bengals quarterback Andy Dalton and keeping the Eagles in the game.

Their improvement has been noticeable. Neither was an opening-day starter, but the playing time for each has increased.

Graham was considered a major disappointment during his first two seasons, but he has four sacks and seven hurries in the three games since Babin's release.

"You're talking about one of the faster guys on the football team - and explosive," Reid said. "He's got speed and he's got a good attitude. It's just a matter of getting him in there and giving him an opportunity."

Cox has 41/2 sacks in the last six games. He became a starter on Oct. 28.

"Earlier in the season, I didn't play a whole lot," said Cox, 22. "Since after the bye week, after that, I've just progressed and taken advantage of the playing time."

Other teams have noticed. Opponents often double-team Cox, putting a guard and center on him to try to block his path. This is a compliment, although Cox is quick to insist he tries "not to get caught up in the hype." And despite the numbers, Cox is not yet happy with the way he is playing.

"I'll never get myself in a comfort position where I feel I've made it, or I arrived," Cox said. "I think that's what happened with a lot of athletes when they start making plays and get noticed."

Both defensive linemen believe they will get better. The roster around them will undergo major changes next season. Their position coach and coordinator likely will change, too, but their lockers will stay in place and their roles on the team will continue to increase.

"We can be as good as we want to be," Graham said. "As long as we keep bringing each other along as we keep growing and getting better, the sky's the limit for us."

Harbor on IR. The Eagles placed Clay Harbor (back) on injured reserve, ending the season of the team's No. 2 tight end. Harbor finished with 25 catches for 188 yards and two touchdowns this season. Emil Igwenagu, who was promoted from the practice squad last week, will be Brent Celek's backup. The Eagles have not filled Harbor's spot on the roster.