PHILADELPHIA (973espn.com) - If you're looking for ways that any NFL season could be derailed, injuries are always going to be at the forefront.

A rash of issues in the defensive backfield had the Eagles struggling post-Super Bowl last season until the ramp up from younger players like Avonte Maddox, Rasul Douglas, Cre'Von LeBlanc and Tre Sullivan stopped the bleeding and enabled Philadelphia to make a run to the divisional round of the postseason.

If you peruse the Eagles 90-man offseason roster now that it's been finalized there are certain positions that lack depth but perhaps none more so than the interior of the offensive line where the Eagles have little proven talent after the starters: All-Pro center Jason Kelce, rehabbing Pro Bowl right guard Brandon Brooks and left guard Issac Seumalo, who just received an extension this offseason.

Gone is the versatile Stefen Wisniewski, a capable starter and one of the better game-day interior backups in the league during his time in Philadelphia with the ability to move seamlessly from center to either guard position.

Outside on the O-Line, the Eagles' depth is in the conversation with the best in football. After all, the oft-maligned Halapoulivaati Vaitai proved good enough to win a Super Bowl with while he filled in for Jason Peters in 2017-18, first-round pick Andre Dillard was a consensus top-15 talent in April's draft and while Jordan Mailata remains greener than the lushest grass in your neighborhood, former offensive linemen like Brian Baldinger and Ross Tucker have gushed about his potential.

Inside, however, the unproven Anthony Fabiano is next in line at center after Kelce with rookie free agent Keegan Render behind him while Matt Pryor, who spent his rookie season as a healthy scratch, will probably spend most of his spring at RG filling in for Brooks, who continues to work his way back from an Achilles' tear.

The Eagles went heavy in the UDFA market when it came to the offensive line, signing three players with draftable grades in Penn State tackle Ryan Bates, Weber State guard Sua Opeta and Stanford Guard Nate Herbig. Each is expected to be thrown into the mix at multiple positions.

One luxury is that Seumalo can play center so if something did happen to Kelce in-game, the Eagles could slip him inside and perhaps bring in Pryor at guard although Jeff Stoutland usually disdains moving parts and prefers not to affect two positions due to one injury. In-house the most likely scenario is getting Vaitai some work inside while the door presumably remains open on Wiz, who remains unsigned.

"Listen, we're always going to cross-train those guys," coach Doug Pederson said Friday when talking about Vaitai perhaps getting a look inside.

The next step for Mailata, though, is an uptick from left tackle to swing tackle.

"This is a guy that I think we can cross-train, and maybe we cross-train him at both tackle spots, left tackle, right tackle," Pederson said. "He's second year now in our system and this will be a big off-season for him. He's a big-bodied guy, and I think he's athletic enough."

Dillard, meanwhile, is so talented the goal is to get him up to speed as the heir apparent to Peters at LT by 2020.

"Andre is different," the coach acknowledged. "We're just trying to get his feet wet with the playbook and get him moving around. At this time, we're just going to kind of keep him where he is at and let him play there."

A source told 973espn.com the Eagles tried to sign a Wisniewski-type player in Brett Jones, a former lower-level starter with positional versatility for the New York Giants who ended up re-signing in Minnesota. The Vikings, though, drafted Garrett Bradbury in the first round to be their starter at center and still have Pat Elflein as well so you can be sure the Eagles will be keeping tabs on things around the league.

For now, though, everyone understands there is an opening.

"I picked the Eagles because it was the best option for me," Bates admitted when asked why he signed with Philadelphia. "Depth-wise. The offensive line right now, they have some injuries, some people getting old. It's a good opportunity for me."

-John McMullen covers the Eagles and the NFL for 973espn.com. You can reach him at jmcmullen44@gmail.com or on Twitter @JFMcMullen