If James Paxton takes a spot at or near the top of the Yankees starting rotation, they’ll have Lance Painter to thank.

Paxton, who the Yankees acquired from Seattle on Monday, was 27 and had spent parts of three seasons in the majors when he showed up to spring training with the Mariners in 2016 and posted a 10.80 ERA in five spring training starts.

Instead of becoming an important part of Seattle’s rotation, the left-hander instead found himself back with Triple-A Tacoma, with Painter, the team’s pitching coach. The two tried to resurrect Paxton’s career after the former first-round pick had shown glimpses of the potential the Mariners knew he had.

Painter hadn’t seen much of his former protégé the previous two years and noticed something off about Paxton.

“There was a significant difference in how he looked,’’ Painter said by phone. “It looked like he was out there throwing sky hooks instead of a three-quarters motion, which is his natural arm slot.”

Painter, now in his 14th year with the Mariners, set about trying to fix Paxton, who he believes inadvertently altered his delivery after a lat muscle injury in 2014.

“To me, he was pitching from a position of weakness,’’ Painter said. “I asked him, ‘When did you feel your best? And he said ‘2014.’ So I went back to the video before he got hurt and we struck gold.”

Painter noticed the difference in Paxton’s delivery immediately.

The more overhanded motion might have led to Paxton’s woes and prior to Paxton’s third start of the season for Tacoma, Painter said he made the discovery in Paxton’s delivery.

At first, Paxton still wasn’t getting his arm low enough. That’s when Painter said minor league instructor Mike Micucci was long-tossing with Paxton and told him, “Just throw it like you’re pitching sidearm.”

It worked.

But even though Paxton went from throwing 91 MPH to the mid-90s, Painter knew the real test would come in a game.

“I remember sitting in El Paso before the game thinking, ‘If this doesn’t work, I’m going to get my butt chewed,’’’ Painter said.

Paxton, who had given up seven runs in just 2 1/3 innings in his previous outing against Albuquerque, tossed six shutout innings versus El Paso, starting a string of four starts in which he gave up just two earned runs in 24 1/3 innings.

“I was expecting it to be a two- or three-week process,’’ Painter said. “But once he found the arm slot, he kept it.’’

He was called back up to Seattle on June 1 and promptly gave up eight runs — three earned — in 3 2/3, but struck out seven. Paxton then gave up just one earned run in 12 1/3 innings over his next two starts, fanning 17.

Paxton has since emerged as one of the top arms in the game, although injuries have prevented him from completing a full season.

The Yankees hope to keep him healthy and let the 30-year-old develop into a top of the rotation starter after giving up lefty prospect Justus Sheffield and two other minor leaguers for him.

Painter was also Paxton’s pitching coach with Double-A Jackson in 2011-12 and used tape of Andy Pettitte to get Paxton to improve his time to the plate and stop opposing baserunners from running wild against him.

And he is confident Paxton will be fine in The Bronx despite other pitchers having struggled in the spotlight.

“I’d be surprised if he got fazed by New York,’’ Painter said. “With James, what you see is what you get. He’s come a long way and now he’s in the prime of his career. It’s going to be fun to watch what he does next.”