Where’s Eagles rookie Milton Williams? He played left end against the Steelers and did OK in his NFL debut.

Rookie defensive lineman Milton Williams has been kind of a Where’s Waldo player for the Eagles in training camp. Defensive coordinator Jonathan Gannon and defensive line coach Tracy Rocker have moved the third-round pick around, using the 6-foot-3, 284-pounder both inside at tackle and outside on the edge.

“The advantages are we get to accentuate his skill set a little bit,” Gannon said last week. “And it’s a little bit matchup driven. We want to see him play on the center, on the guards, on the tackles.

“We’re still kind of figuring out — with all of our guys, but especially Milton — what best suits him so he can be successful.”

On Thursday night at least, what suited him best was the outside. Williams played a little more than 20 snaps in the Eagles’ 24-16 preseason loss to the Pittsburgh Steelers at the Linc, all of them at left defensive end.

Gannon played most of his defensive starters just one series against the Steelers. Williams entered the game with 5 minutes, 42 seconds left in the first quarter and played the rest of the first half. He collaborated with tackle T.Y. McGill on a second-quarter sack of Steelers quarterback Mason Rudolph.

“I was working the [right] tackle,” Williams said of Joe Haeg. “I was working the bull rush on him. I felt he was leaning out, and just snatched him real quick. I was going to get [the sack], but the [right] guard came over and got me, and that freed up T.Y.

“I’m happy for him. I celebrated with him afterwards.”

You might recall that the drafting of Williams by the Eagles in April was not without controversy.

General manager Howie Roseman traded down three spots in the third round, effectively forfeiting an opportunity to take Central Florida cornerback Aaron Robinson, who was selected by the New York Giants with the 71st overall pick, or North Carolina State’s 6-2, 320-pound defensive tackle Alim McNeill, who was taken by the Detroit Lions with the 72nd selection.

The Eagles, who got a sixth-round pick in the trade-down, took Williams at No. 73. ESPN, which had a camera in the Eagles’ war room, caught a clearly miffed Tom Donahoe, the team’s senior personnel adviser, turning away from Roseman when he tried to celebrate the pick with a hand slap.

Donahoe favored McNeill, a huge run-stopping interior lineman, over Williams, who many NFL scouts felt was a ‘tweener who isn’t big enough to play tackle.

Williams played on the outside his first two years at Louisiana Tech before being moved inside his last year there. He had 4 ½ sacks and 10 tackles for loss last year at tackle, but he often got manhandled by bigger, stronger interior offensive linemen.

“I’m pretty comfortable playing both” inside and outside, the rookie said. “They trust me to know both spots. I’m doing my best to get as much confidence as I can in there. Let them know that whenever they need to move me around, they can do that.”

Williams had an impressive showing at his predraft pro day in the spring, running a 4.62-second 40 and registering a 38 1/2-inch vertical jump, as well as benching 225 pounds 34 times. How much that workout played a role in Roseman’s preference to draft Williams over McNeill is uncertain.

Williams has short arms — just 31 1/2 inches — which can be a major disadvantage on the outside where you have to shed blocks and get around bigger, longer-limbed offensive tackles.

Williams admitted to being a little nervous Thursday before his pro debut.

“This morning when I woke up, I was kind of nervous to know that I finally was going to be playing in my first NFL game,” he said.

“But once I played the first snap, I got settled in a little bit. I got a little bit more comfortable and just tried to do what I know. I’ve been playing football my whole life. It was a dream come true tonight.”

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Williams said he wasn’t surprised that he played strictly at left end against the Steelers. Whether that’s going to be the case next week and the week after that remains to be seen.

“I kind of expected it,” he said. “They want to move me around and see where I’m more productive and see what my skills are and where I’m best at. I’m happy playing both. I want to keep getting better at both.”

The second-quarter sack on which he collaborated with McGill clearly was the highlight of Williams’ NFL debut. He struggled a couple of times setting the edge against the run, but overall he played pretty well.

“I played OK,” he said. “It wasn’t how I want to look every down. But it’s like coach [Nick] Sirianni says; Just get 1% better every day. I’m going to go watch the tape and see what I can do to get better next week.”

What specifically does he feel he needs to improve?

“Just technique things,” he said. “Keep my pad-level down. Keep my eyes clean. Make sure I’m looking at the right things. Playing my keys. Playing my technique and things like that. You watch film, and you can always get better at those things.”