It looked familiar Thursday when the Eagles entire first-team defensive line retreated to the sideline during the first quarter and a new group entered the game. On the next drive, the starters returned. This was a strategy that the Eagles utilized last year, when they entered the season raving about their depth on the line. They used mass substitutions like a hockey team.

We all saw that how turned out.

After talk of setting the NFL sack record in 2012, the Eagles ended up with 20 fewer sacks than the previous season. A Pro Bowler was cut, and the defensive line coach was fired shortly after.

Comparing this group with 2012 is difficult as the scheme changed, and it's almost an entirely different set of players. Jason Babin, Mike Patterson, and Cullen Jenkins are among the high-profile players who have left, and Trent Cole and Brandon Graham are now outside linebackers.

But what remains is excitement about the depth on the defensive line. Last year, the preseason banter was about how there were "eight starters" on the D-line. Coach Chip Kelly said that there's not much drop-off between the team's first and second units this season, which could be a reason the Eagles keep a rotation this year.

"It depends on the situation," Kelly said. "I think sometimes when the drives get a little bit longer because of the talent level of some of those other guys, there's not a big drop off. . . . The ability to have six guys and seven guys that can rotate through there I think makes you better."

This group is less distinguished than last year's. And the depth might not signify an abundance of talent as much as the parity of the talent.

The starting unit - at least at this point - is Fletcher Cox at right defensive end, Isaac Sopoaga at nose tackle, and Cedric Thornton at left defensive end. The next group is Clifton Geathers, Bennie Logan, and Damion Square. Vinny Curry will be on the team, too, so he's in the mix for the defensive end spots. It's likely that there will be five new players on the defensive line.

Cox is the best player of the group. A 2012 first-round pick, Cox is perhaps the defense's finest player and the most likely candidate to make the Pro Bowl this season. Logan has enough versatility to challenge Thornton for a starting spot, although Thornton had a strong performance in Thursday's preseason victory. Logan, a 2013 third-round pick, has excelled throughout the summer.

What's noteworthy about the group is how young it is. Kelly has described it as a strength of the defense, which might not say much about the Eagles defense. But it's promising for Kelly's future. Only Sopoaga and Antonio Dixon are 28 or older. Most of the linemen expected to be on the roster are 25 and younger, with the 22-year-old Cox the foundation player.

Aside from Cox and Curry, the players in the top seven were not high draft picks. An example is Square, an undrafted rookie out of Alabama who is likely to make the roster. Kelly called Square a "great technician." He doesn't play like a rookie and has worked his way into the rotation, Kelly said.

Curry is a player to watch, and he wasn't even in the top six last week. He was a second-round pick in 2012 who could not crack the rotation. Every other defensive end that remained on the roster from last season was moved to outside linebacker except Curry, who added bulk but did not seem an ideal fit for the new defense.

His performance has been noticeable in the preseason. Curry recorded one tackle for a loss, two quarterback hits, and half of a sack. At the least, he can be a situational pass rusher in the nickel. But he could also prove to be more.

"I'm in the rotation. Even when they run-block, I do my technique," Curry said. "I'm definitely trying to climb up. Right now, I'm trying to keep working."

The rotation will evolve, especially as the roster is trimmed and Kelly determines how many players to activate on Sundays. Part of the reason the Eagles used the substitution pattern they did in the first preseason game was for evaluation purposes.

The depth impressed Kelly, but Eagles fans have heard that before. This year's linemen, with lower profiles than last year's, must prove that depth translates to results.

Click here for complete coverage of Philadelphia Eagles training camp.

Wang released. The Eagles released offensive lineman Ed Wang on Monday. Wang, a 2010 fifth-round pick by the Buffalo Bills, was acquired during the offseason. He had been injured most of training camp and was unlikely to make the roster. The Eagles roster is now at 88 players.