So what changes? Or doesn't? What might be different now that linebacker Marcus Smith and wide receiver Jordan Matthews figure to be contributors? Or will it be more of the same, for better or worse?
Start with Marcus Smith. A lot of smart people think the Eagles are going to have to work him in slowly, situationally - and that his best situation will be rushing the passer in obvious passing downs. That might end up being true, too. But the more you think about it, if the Eagles' coaching staff can teach him how to be a reasonable facsimile of a run defender by the end of the summer, Smith's best situation might end up being first down.
The run business is what Smith needs to learn - but you can learn it if you arrive with the requisite base of strength. We'll know that soon enough. If he can be taught to set a somewhat credible edge, most of the time, Smith can play on first down.
You have to remember how last year went. On first-and-10, the Eagles allowed 81 first-down passes, most in the league. They allowed 7.1 yards per pass attempt in that situation. Among the 12 playoff teams, that put them 10th. What it did, more than anything, was set in motion this relentless tide that we all saw. The Eagles were a lot better at the end of the season, but they still couldn't get off the field nearly quickly enough. You can argue about why, and about who is to blame, but 7.1 yards per pass attempt is a tough swallow, series after series.
So maybe, if you can swap Smith for Trent Cole on first down, you get Smith's pass-rush quickness and you also get his cover skills, which are presumably better than Cole's. Because of those cover skills, you also, maybe, will free Connor Barwin to rush the passer once in a while. I'm a charter member of the Free Connor Barwin movement. He was penalized last season because of his versatility - but his skills do include going after quarterbacks.
The Eagles would benefit from that added dimension. Cole would benefit, at this point in his career, from a more defined role as a quarterback killer. This could work, if Smith can grow into the job quickly. If not, it's hard to see the improvement the defense is going to need in getting off the field.
The other side of the ball is more intriguing. We talked about identity on first-and-10, and the Eagles' offense was as clearly identified as any in the NFL with their signature formation: one back, one tight end and three wide receivers.
The Eagles used that formation 71 percent of the time last year on first-and-10. A quick look did not reveal anybody in the league close to that number, other than Denver at 66 percent. The Eagles and Denver were two of the fastest-paced, highest-scoring offenses in NFL history - the Eagles were faster, the Broncos more potent - and this is how they went about it. One other thing: Both teams ran the ball out of that formation at a much higher rate than the league average.
But now DeSean Jackson and Jason Avant are gone, and Jeremy Maclin and Matthews are in - different players, skills and levels of experience. We all wonder how it's going to work without Jackson's super-speed element in the offense, but Matthews' size offers some red-zone possibilities that did not exist before. Then there is the fact that Matthews' college specialty is also a local favorite: Chip's beloved bubble screen, which is the rubber baby buggy bumper for a new Eagles era.
Still, we don't know until we see it. Which makes you wonder: Will three wideouts still be the signature?
Because the Eagles have a heck of an alternative. While this obviously has a lot to do with where and when the formation was deployed, just know this: Tight end Zach Ertz was on the field, normally as the second tight end, about 40 percent of the time last year, but he was on for about 60 percent of the offensive touchdowns the Eagles scored.
Both Ertz and the formation were dynamite. Everybody seems to want to see more of it. Will we? Will first-and-10 still look like first-and-10? Only Chip Kelly knows, and maybe not even him.
On Twitter: @theidlerich