FOXBORO, Mass. — Adam Butler stood nervously on the New England Patriots’ sideline with his hands grasping the inside neck of his shoulder pads, helmet nowhere to be found, as his final opportunity to prove he deserved to make the team was passing by before his very eyes.

The undrafted free agent defensive tackle assumed the worst when informed he would suit up but not play in the Patriots’ final preseason game of the summer against the New York Giants. As the Patriots’ defense took the field for the game’s first series, in his place were Darius Kilgo, Geneo Grissom, Woodrow Hamilton and Michael Bart on the defensive line.

Standing next to the rookie out of Vanderbilt were Trey Flowers, Dont’a Hightower, Alan Branch and the rest of the Patriots’ defensive starters. And as they came up to Butler, the look on his face turned from concern into a proud ear-to-ear smile.

“I was alarmed, because at first I thought it was a bad thing,” Butler told on Tuesday. “I thought that they had seen what they wanted to see, and it was like, ‘Eh, we aren’t going to take this guy.’ I wasn’t sure. But after some of the older guys came up to me and told me ‘congratulations,’ I was like, ‘What? How do you know before me?’ But they’re vets.”

Suddenly, he looked like the younger brother asked to play pickup hoops with the older kids. Butler never entered the game, because he already had made the Patriots’ 53-man roster. It’s customary for NFL starters and roster locks to remain on the bench for the final preseason game.

Butler’s inclusion on the initial active roster was more than well-deserved. Butler ripped through Patriots training camp, seeing snaps on the first-team defense by the sixth practice of the summer. He handily beat Patriots offensive linemen in 1-on-1s and Jacksonville Jaguars blockers in joint practices. In three preseason games, he recorded three QB hits, five hurries and drew a hold as a pass rusher. He was similarly disruptive in the run game, bursting through the line with regularity.

If fans of Vanderbilt suddenly didn’t recognize this Adam Butler, it was understandable. Butler went to Vandy as a 320-pound offensive lineman. He got fired up during a rib-eating contest — no, seriously this is true — and was moved to defensive tackle.

When Butler came to the Patriots, he weighed 305 pounds. Fast-forward four months and Butler now weighs 280 pounds.

“It was probably a combination of stress and hard work through OTAs,” Butler said.

The initial plan after meeting with Patriots head strength and conditioning coach Moses Cabrera was to drop Butler’s body fat. It came in at 26 percent. It’s now down to 19.6, and Butler suddenly has a lot more quickness and versatility. Now he can start adding more muscle to his frame and bulk back up with “quality weight.”

“I’d say his weight now is better than what it was,” Patriots head coach Bill Belichick said last month. “Could it be more? Maybe. We’ll train and see, but he has a good frame so it wouldn’t surprise me to see him add on some quality weight. It’s hard to add it during training camp, but once the training progression changes a little bit during the season or certainly in the offseason that there will be an opportunity for that to happen.”

At 6-foot-4, 280 pounds, Butler has the length, strength and quickness to play inside at defensive tackle or outside at defensive end. He manned both roles in preseason and could be used as the Patriots’ top interior pass rusher in 2017.

And even though he trusted his veteran teammates that he had made the roster last Thursday, Butler still was overtaken by emotion when he officially found out he made the team Saturday.

“Man, I was in my room, and I just dropped down to my knees, and I just thanked God,” Butler said. “It was a lot of work, a lot of sweat, blood and even tears. And it paid off.”

Thumbnail photo via Raj Mehta/USA TODAY Sports Images