Doug Pederson scanned the locker room after the Eagles’ comeback victory over the New York Giants and spotted Halapoulivaati Vaitai in the back corner with other offensive linemen.

“V!” the coach said, prompting a round of cheers and applause.

Pederson had already singled out several reserves, including Greg Ward, Boston Scott, and Josh Perkins, who had performed admirably in place of injured regulars. It was an initiation into an expanding group of players who have been called upon as the NovaCare Complex has come to resemble a medical ward.

But for Vaitai, it was been there, done that, which could explain Pederson’s late notice during his postgame speech, which the Eagles released video of. In four seasons as a backup, he has jumped in mid-game as a replacement 20 times. On Monday night, he filled in for right tackle Lane Johnson after he left in the second quarter with an ankle sprain.

In seven games this season, Vaitai has been plucked from the bench. While tackle was predominantly his position in his first three years, the Eagles added guard to his plate in the offseason. And he has played both guard and tackle spots this season, and sometimes two in one game.

“We ask a lot of V,” offensive coordinator Mike Groh said Wednesday. “He fills in at a bunch of spots in the line. And kind of an unsung hero, so to speak.”

This Sunday at the Redskins, though, Vaitai will make his first start of the season with Johnson all but officially out. He has been down that road, too, having made 19 previous starts.

Vaitai has had his struggles, beginning with his first career start in Washington as a rookie three years ago. But he settled down during that stretch, and especially a year later, when he spelled the injured Jason Peters at left tackle all the way to the Eagles’ Super Bowl victory.

He has had his setbacks since, but Vaitai’s best games have often come when he has had a week to prepare as a starter, and more so consecutive weeks, which could be the case with Johnson’s prognosis uncertain.

“There’s been a lot of ups and downs,” Vaitai said Thursday of his last four seasons. “You’re excited for the first game. You want to do really good, but you end up doing worse. And then a lot of guys just told me, ‘Hey, man, just calm down. Just be yourself.’ And so, that’s what I’ve been doing — be myself and learn along that way.”

Sunday could be another opportunity for Vaitai to raise his stock with free agency looming this offseason. His first career start, which came when Johnson began serving a 10-game suspension for violating the NFL’s performance-enhancing-drug policy, seems in some ways so long ago.

The fifth-round rookie had the unenviable task of facing Pro Bowl linebacker Ryan Kerrigan in his first game action, and the results were predictable. Vaitai allowed 2½ sacks and several more hits on quarterback Carson Wentz in a 27-20 loss.

Kerrigan, though, is unlikely to play Sunday because of a calf injury.

“I wish he was coming back,” Vaitai said.

In the visitors’ locker room at FedEx Field after his first start, Vaitai answered questions quietly while wearing a shirt with the axiom — The worst days are the days you must show up — aptly written on the front. But better days were ahead as Vaitai settled down.

A knee injury prematurely ended his rookie season after six starts,. But he was back in the lineup a year later, first when Johnson missed a game against the Panthers, and two weeks later, when Peters suffered a season-ending knee injury against the Redskins.

There was the expected downgrade, but Vaitai improved with each week. By the time the NFC championship game came around, he kept All-Pro Vikings defensive end Everson Griffen in check for the entire game.

Vaitai wouldn’t overstate the change in preparation as a backup as opposed to a starter, though.

“When I get ready during the week, I try to train myself like I’m the starter,” Vaitai said, “because you never know where you’ll have to go — left guard, left tackle, right guard, or right tackle. I’m just trying to prepare myself to get ready.”

He conceded that the additional first-team repetitions at one spot both during the week and before the game were beneficial. Right guard Brandon Brooks said that he no longer has to work out kinks with Vaitai because they’ve played alongside each other so many other times.

“Big V, in particular, I know how he plays,” Brooks said. “I know what he’s thinking. He knows what I’m thinking. Same like me and Lane. It’s not a big deal.”

Brooks’ Achilles tendon injury compelled the Eagles to move Vaitai to guard. He ended up playing only 20 snaps in the first game until Brooks returned full time. But his versatility could potentially increase his marketability.

“Right now, I’m not worried about [free agency]. I’m worried about this week,” Vaitai said. “It’s the most important game. All that stuff can take care of itself in the offseason.”