When you back up Jason Peters, you better be ready to play at a moment’s notice. The Eagles left tackle has missed at least one snap because of injury in 38 of the last 91 games he’s played. Peters will sometimes come back, but other times – like in Sunday’s Vikings game when he left with a knee injury – he won’t return.

Andre Dillard is just the latest to be Peters’ backup, but he’s no stopgap. The rookie was drafted in the first round to be the eventual replacement and that moment may come sooner rather than later if the 37-year-old Peters’ knee continues to sideline him.

Eagles coach Doug Pederson said Wednesday that the timetable for Peters’ return was “week to week,” which all but guarantees that Dillard will get his first NFL start Sunday at the Cowboys. Dillard had logged only 12 snaps at left tackle before Sunday, but he was tossed into the fire at Minnesota and played 47 of 65 snaps against a strong defense.

“He had some good plays,” Pederson said Monday. “He had some bad plays, quite honestly.”

In other words, Dillard performed like most rookies would under similar circumstances. Pederson equated his outing to that of Halapoulivaati Vaitai’s first start three seasons ago. But Dillard didn’t struggle nearly as much, and he hardly received assistance from other blockers.

The Eagles won’t likely treat Dillard, who has more ability than Vaitai, with kid gloves. Nor should they.

“That’s why we drafted him,” Pederson said Wednesday after he announced Peters’ injury update. “We have total confidence in Andre.”

Here’s a look at the film of how Dillard, who wasn’t available to reporters Wednesday after practice, blocked in his first extended playing time:

Dillard’s first play

Peters left for the first time after the Eagles’ 10th offensive play. He appeared to tweak his knee when he kicked out during a Miles Sanders 3-yard rush. Dillard (No. 77) jumped in on second down and Vikings defensive end Everson Griffen (No. 97) drove him back. He was already off balance when he appeared to trip on running back Jordan Howard (No. 24) and fell backward.

Quarterback Carson Wentz (No. 11) somehow escaped and hit Alshon Jeffery (No. 17) for a 2-yard gain, but it was a rough start.

Eagles center Jason Kelce: It looked pretty clear to me that he tripped. Not that he was in a great position to begin with. I think that made it a lot worse to the observer than it probably was.

Dillard has been taking first-team practice snaps since the spring, so he had been prepared for the moment. Still, jumping in against an accomplished edge rusher had to be a shock to the system.

Pederson: He gets a lot of practice reps during the week and when he does get a chance to play, it’s not like it’s the first time. Now, it’s game speed obviously, but it’s not the first time.

Dillard’s second play

On the next play, the Vikings threw a stunt at Dillard and left guard Isaac Seumalo (No. 73). The Eagles linemen picked it up, but there was enough inside pressure that Wentz felt compelled to roll out. His third down pass was tipped and fell to the turf.

Communication and chemistry between the tackle and guard are vital when handling stunts and twists.

Seumalo: I feel good about it. First of all, he’s a good player. That helps. He’s knows what he’s doing and he’s smart. He makes the transition easy. But I’m sure teams will test him all year.

Peters’ last play

Peters (No. 71) returned for the next series, but he left after the first play of the Eagles’ following possession. The Eagles trailed, 24-3, at the time.

Pederson: The one thing I love about J.P. is how he fights through and battles through injury. That’s first and foremost. He’s a tough guy, and he’s an anchor.

If Peters is inactive Sunday, it’ll be the first full game he’s missed since the Super Bowl in January 2018. The 9-time Pro Bowler said during the offseason that compensating for his right knee, post-ACL surgery, factored into various nagging injuries he had last season. It’s unclear if his current injury is with the same knee.

Dillard’s return

Dillard settled down when he returned. He got a break from Griffen, a three-time Pro Bowler from 2015-17, on this pass play. Linebacker Anthony Barr (No. 55) has been to multiple Pro Bowls, as well, but rushing the quarterback isn’t his specialty.

Barr couldn’t get around Dillard’s vertical step as Wentz hit Sanders for a 32-yard touchdown.

The Eagles’ front office and their coaches have raved about Dillard’s footwork since they traded up four spots to draft him No. 22 overall.

Eagles right tackle Lane Johnson: He’s athletic. He can do everything you want. As he grows and matures, he’ll get stronger, anchor will get better. The thing with tackles, you just got to go and play.

Dillard’s improvement

A series later, Griffen tried a spin move. Dillard held his ground, although he fell just as Wentz slid to his left and hit Jeffery for 23 yards.

If Dillard’s quick release off the snap looks familiar, it’s because he aped it from Peters.

Kelce: If you’re a tackle in this league you have to be able to get off the ball and do it like you’re shot out of a cannon. The ends are too fast or too good in this league. And if you’re caught in a position where he’s equal with your hip line … you’re in a bad [spot] because then you feel like you need to open up. … Once you open up and you get into the mode where you got to run then you’ve lost all your balance and your framework.

Dillard in space

Dillard’s measureables in size and length were in the lower percentages for tackles at the NFL combine. But he tested well in speed and agility drills like the broad jump (99th percentile), 20-yard shuttle (98th), 40-yard dash (94th), and 3-cone drill (89th).

On this screen pass to Jeffery, Dillard kicked out to block Barr in space. He got to his mark, but Barr knocked him back on his rear. Jeffery, though, still gained three yards, enough for a first down on second-and-1.

Dillard should, in time, become a tackle the Eagles utilize in space. But how he in-line blocks will be of the upmost importance. If he struggles, Pederson will likely call on Peters to slide protection his way or help Dillard with chip blocks.

Pederson: The guys around him, he’s not on an island obviously, he’ll get a lot of help from the guys, starting with Jason Kelce and we go from there.

Dillard as a run blocker

Dillard surprisingly fared better as a run blocker than in pass protection Sunday. One of the pre-draft concerns about him as a prospect was that he wasn’t asked to run block a lot at pass-happy Washington State. But his hand work vs. Griffen on this Howard 9-yard carry was efficient.

Kelce: He’s got some stuff to learn about [run blocking] still. He just hasn’t done a lot of it. He’s got to get the reps.

Dillard’s pass blocking technique

Dillard continued to struggle against bull rushes, though. Wentz hit Nelson Agholor (No. 13) for a 23-yard gain on this pass, but Griffen walked the tackle right back into his quarterback.

Pederson: He’s going against a great defensive end. Griffen is a tremendous D-end and I have a lot of respect for him and his game and there were times where Andre looked really good and then there were times when he got a little off balance.

Dillard had a difficult time maintaining his weight in college. The Eagles have him listed at 6-foot-5, 315 pounds, but he looks noticeable smaller standing next to the team’s other tackles. He could also stand to benefit from a full offseason of NFL weight training.

Kelce: Some guys are bigger by nature and they’re going to be a little bit better with it. He’s a very athletic guy. He’s not small, but he’s not enormous either. He has such great feet right now. If he has a weakness right now, it’s probably [strength]. But I don’t think it’s as big of a weakness that it’s probably being played up to be.

Late in Sunday’s game he got matched up against Griffen’s counterpart, Danielle Hunter (No. 99), who is about 20 pounds lighter. Hunter was able to push Dillard back, too, as he did here when he sacked Wentz.

Johnson: A lot of timing can help, too, with the hands and feet, being synchronized so you can control that power better.

Pederson: We have to do some technique work with him still some more. Just a young player in that atmosphere, but I thought overall, he did some really good things.