Despite using four substitutes, the Eagles offensive line including reserve Andrew Gardner (66) and starter Todd Herremans (79) did not give up a sack against Pro Bowl linebacker Ryan Kerrigan (91) and the Redskins defense. Photo by Jeff Burke/contrastphotography.com

Watching the Eagles offensive line perform during the preseason, it became obvious that the Birds had depth at a position that was one of the biggest strengths during the 2013 season that produced a 10-6 record and an NFC East title for rookie head coach Chip Kelly.

No one though could have imagined that depth would be tested to the level it has been during this young season.

During the Eagles thrilling 37-34 win over the Washington Redskins on Sunday at the Linc, their third victory of the season without a loss, the Birds lost standout center Jason Kelce in the third quarter with an abdomen injury.

Enter second-year center David Molk.

Molk is small by major college standards at 6-foot-1, 290 pounds let alone the NFL, but after a shaky first couple of plays did just fine.

Not long after that, left tackle Jason Peters – arguably the best offensive lineman in the NFL right now – was ejected from the game after punching out Redskins defensive lineman Chris Baker, who was ejected for a cheap-shot hit that leveled Eagles quarterback Nick Foles. Foles did not miss a play.

The lone starter left, Todd Herremans, was moved from right guard to right tackle. Right tackle Andrew Gardner, a five-year veteran, was moved to left tackle. Gardner was playing in place of Allen Barbre, who had been playing for starting right tackle Lane Johnson, who is suspended for the first four games, until an injury in the opener ended Barbre’s season.

Dennis Kelly was already playing left guard in place of All-Pro Evan Mathis, who is out for eight or nine games with with a strained knee. Kelly was moved to right guard and newcomer Wade Smith, a 12-year veteran, entered the game in the fourth quarter at left guard.

Got that? Bottom line?

The Eagles played the fourth quarter of a crucial NFC East game and won with four substitutes playing on the offensive line.

“They coach us up really well,” said Gardner at his locker after the Redskins game. “They do a good job of making sure everybody knows how to play multiple positions (on the o-line). We just don’t understand like ‘Oh what do I do if I’m a right tackle’ but understanding the entire play and what everybody is trying to get done. Everybody’s switches today (against the Redskins) was back to something they had done before. Dennis was a right guard, he did that all preseason (and in 2012), Todd (Herremans) used to play left tackle, I played a lot of right tackle during my career so I think that really helped a lot with that switch. The coaches know that and purposely assigned guys that have a little bit of versatility…so if if it hits the fan, you can make those adjustments.”

While the Eagles running game was not productive against the Redskins, the passing game certainly made up for it.

Foles was 28 of 42 for 325 yards, three touchdown passes and no interceptions. Incredibly he was not sacked once despite the patchwork line.

Kelly talked about how his coaching staff deals with injuries and substitutions on the offensive line and of course the toughness of Foles.

“That’s what you’ve got to do,” Kelly said. “You only have seven guys active on game day. Matt Tobin (injured backup lineman) couldn’t go, so it would’ve had to been (Kevin) Graf if we had to go with another man, if we were going to keep eight up. But we just went with the seven that were healthy and then you lose two more. That’s what you’ve got to do. You’ve got to be able to battle in this league. They were playing with their backup quarterback. They lost their quarterback last week, so that’s what this deal is all about. I think everybody understands going in that, except for maybe the first game. Are you going to be at full strength and then can you endure, and I thought they made plays when they had to, and then to be able to score as many points as we did with that group, I think it’s a credit. I also think Nick [Foles] just stood in there today, and that’s one thing, I said it before about him and I knew it because when I played against him in college, he’s going to stand in there, he’s a tough sucker. He got hit a lot today. It’s a victory, it’s a division victory, so we’ll take it.”