NEW YORK - It would be easy to look at the Seahawks following their dominating 43-8 victory over the Broncos in Super Bowl XLVIII and envision what might have been for the Eagles, especially on the defensive side of the ball.

The Eagles, in theory, could have had Seattle's entire starting lineup, and, in fact, once had linebacker Chris Clemons on their roster. But the same could be said for virtually every other team in the NFL, and detailing every missed opportunity would be an exercise in futility.

Yes, the Eagles could have selected linebacker Bruce Irvin in the first round of the 2012 draft, but then they wouldn't have defensive end Fletcher Cox.

Not even bypassing safety Earl Thomas for linebacker Brandon Graham or opting for linebacker Mychal Kendricks over linebacker Bobby Wagner matters at this point because the coaching staff has changed, and with it the defensive philosophy.

Chip Kelly wants big, physical defenders that can fly to the ball, like the guys the Seahawks have been stockpiling over the last four years, with coach Pete Carroll and general manager John Schneider picking the players.

"John Schneider has been the one who's been out, chasing down the guys who can fit into our program," Carroll said Monday during a news conference with one of those players, Super Bowl MVP linebacker Malcolm Smith. "We've always wanted big guys and physical guys, but if you can't run, you can't play for us, so we've fortunately found guys who are big and fast."

Sounds simple enough, but those players don't grow on trees, and they don't all come in the first round. Talent evaluators must think outside the box or have the foresight to project players who may fall into the latter rounds, especially if they suit the needs of a specific scheme.

Seahawks cornerback Richard Sherman and safety Kam Chancellor weren't drafted until the fifth round. Cornerbacks Byron Maxwell and Walter Thurmond were fourth- and sixth-round picks. Linebacker K.J. Wright came in the fourth round. Defensive end J.R. Sweezy and Smith were seventh-round selections.

All four of Seattle's "Legion of Boom" defensive backs began their football-playing careers on offense. Sherman was originally recruited as a receiver. Eagles general manager Howie Roseman has often talked about expanding the pool of prospects when looking to find fits, especially in the defensive backfield.

The Seahawks also connected on their early-round picks (Thomas, Irvin, Wagner) and were successful in free agency with defensive ends Cliff Avril and Michael Bennett. But you don't build championship defenses and arguably one of the best ever without great depth.

The Eagles aren't likely to catch the Seahawks or the 49ers - probably the league's second-best team last season - by building a defense with as much ammunition. They're too far behind already, and Kelly was brought in for his offensive innovations. He has enough firepower on offense to compete.

But Kelly and Roseman need to add pieces to what was an overachieving defense in 2013. They can't just snap their fingers and remake the entire starting lineup or even acquire more than two or three new starters.

The defensive line is set with Cox, Cedric Thornton, and Bennie Logan. Outside linebacker Connor Barwin will return and so might Trent Cole. Kendricks will be back inside and maybe DeMeco Ryans. Cornerbacks Cary Williams, Bradley Fletcher, and Brandon Boykin are expected back. And safety remains up in the air, although it's possible both Nate Allen and Earl Wolff return as starters.

But there is still plenty of room to add talent that can contribute in 2014. Carroll's defensive line doesn't have four starters, but eight who can rotate. He went with Avril, Bennett, and Clinton McDonald, linemen who typically play in only nickel situations, to start because he could. And the move paid off.

Could Eagles defensive coordinator Bill Davis have started his second unit - Vinny Curry, Clifton Geathers, and Damion Square - at any point last season without giving up something? Kelly often talks about how there aren't any starters, but his defense had too many players play the bulk of snaps last season.

Ryans (96 percent), Kendricks (95), and Barwin (94) were on the field far too often.

Davis did about the best he could with the personnel he was given. Some complained that his schemes were vanilla, but in truth most coordinators would rather play offenses straight up. They just can't because of limited skill sets.

Carroll had the luxury of running some fairly basic coverages - particularly a Cover 3 zone (three defensive backs split deep in thirds) - because Sherman can lock down receivers man-to-man and Thomas can safeguard over the top.

Schneider, meanwhile, had the luxury of acquiring free agents such as Avril and Bennett to fill holes and will have the opportunity to extend contracts for Thomas and Sherman because they have quarterback Russell Wilson under a third-round deal for another year.

The Eagles are in similar shape because of quarterback Nick Foles' third-round contract. There's a little more uncertainty with Foles than with Wilson, but the Eagles have $20 million in salary-cap space if they want to sign a few mid-tier free agents.

But they must continue to build their defense through the draft and hit more than they missed under the previous regime. The Seahawks and 49ers are at another level right now, but as those two teams showed, the gap can be closed quickly.