Sometimes you have to backdoor intelligence gathering when it comes to the modern NFL in which teams dispense information like they are guarding state secrets.

So much of what the Eagles want to run on the offensive and defensive sides of the football in 2021 is an unknown right now, further obfuscated by a scaled-down offseason with no teamwork.

We're left to read the tea leaves and surmise Nick Sirianni will use a lot of Frank Reich concepts. On the defensive side, most have looked to Mike Zimmer being the biggest influence on Jonathan Gannon, something the Eagles' new defensive coordinator admitted.

"The first guy that I worked for in the NFL when I was defensive quality control in Atlanta, was Mike Zimmer," said Gannon. "...Then kind of went our separate ways and then got back with him in Minnesota. So off the top of my head, Coach Zimmer was a huge influence on me, and he was a DB guy to start by trade. So that was pretty cool."

Gannon is no Zimmer clone, however, and noted he's not looking to simply stencil Zimmer's philosophy over the NovaCare Complex.

That said, one staple of Zimmer's well-regarded defenses looks like it's on its way to Philadelphia, his trademarked A-gap looks designed to put pressure on the opposing quarterback both pre-snap and post-snap.

The cat was let out of the bag by veteran pass-rusher Ryan Kerrigan, who has been vague to the local media since signing but opened up a bit to Chris Russell, a long-time reporter who has covered the Washington Football Team for its flagship radio station, 106.7 The Fan.

"I just had [Kerrigan] on my radio show a couple of weeks ago right after he signed with Philadelphia and he told me he was really intrigued by what the new defensive coordinator and system that they're setting up there in Philadelphia," Russell told SI.com's Eagle Maven on BIRDS 365.

Kerrigan is going to be used in multiple roles, according to Russell.

"[The scheme] is going to allow him to not only be a 4-3 end at times but also maybe work in some principles of the 3-4 edge and maybe kick down inside in nickel like closer to the football, over the center," Kerrigan told Russell.

The former has been seen at OTAs where linebackers coach Nick Rallis would set players like Genard Avery, Joe Ostman, and rookie Patrick Johnson off to the side to work on edge rushes while the latter defines Zimmer's sugaring of the A-Gaps.

In Minnesota, that's the role of Eric Kendricks and Anthony Barr or Eric Wilson when Barr went down with a pec injury last season.

It's likely no coincidence that Wilson signed in Philadelphia in free agency and those A-gap looks in 2021 for Gannon could be Wilson and Kerrigan, standing over the center to confuse the opposing QB.

The problem comes in with Kendricks and Barr being so versatile and able to blitz or bail in coverage if need be. Kerrigan could certainly do the former but the latter would be asked a lot after a decade-plus of rushing the passer.

"I think you can maximize a little bit more out of Ryan Kerrigan because he's not a speed guy, he's not a move guy like with spin moves or rips and all that stuff.," said Rusell. "He's more of a bull rush get your hands into [the O-Lineman] and drive somebody back,. Or you win with strength so to me I think if Philly is using him right. ... I think they should use him more inside where he can get a more straight and direct line and path to the quarterback."

For Gannon, the key seems to be different looks

"Everyone talks about you want to pressure the quarterback, pressure the quarterback. Well, in my opinion, one of those ways is pre-snap, not post-snap," he said. "So what you do is you want to make sure that quarterback - offensive coordinators and quarterbacks right now are really, I feel like, ahead of where they were when I first got into the business as far as knowing where to go with the ball immediately or reading coverages or getting to each progression where they need to get to with the ball.

"You just want to put a little bit of seed of doubt in that quarterback's mind."

Kerrigan could be that seed.

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