BOSTON — Aaron Boone watched the video of Luis Severino’s rehab outing with Double-A Trenton and came away pleased by what the right-hander showed Friday night in his second appearance, as he attempts to come back from rotator cuff inflammation that was followed by a lat strain.

“It was very encouraging,’’ the Yankees manager said Saturday of the 50-pitch, three-plus inning outing. “I thought he looked, certainly, a lot better than the first time out, which was like a first spring training start.”

Boone said Severino looked “a lot sharper.”

“He had good life on his fastball and good shape on his slider,’’ Boone said before the Yankees beat the Red Sox, 5-1, at Fenway Park. “He threw a lot of changeups with pretty good results. It was a big step forward for him.’’

After the game, Boone said no decision had been made about where Severino would pitch next.

The team will determine what setting would set him up for success, whether it’s with the Yankees or in a “more controlled environment” of another minor league outing.

Either way, Boone said the plan is to use Severino as a starter and to continue building up his pitch count heading up to the postseason.

“To me, he’s demonstrated enough to be an option [here],’’ Boone said.

The most important thing for Boone is that Severino feels good physically.

“Over the last month, in his mind, he’s confident he’s through his injury and building really good momentum with every bullpen, every outing,’’ Boone said. “We have a lot at stake moving forward here and we want to make sure we do everything we can to optimize that he’s a part of things.”

Boone also watched Dellin Betances’ outing from Friday with Trenton, a scoreless inning that included a walk and a hit by pitch in his first rehab appearance.

Boone called it “a positive step” for Betances, as well, although the right-hander was “rusty.”

He could pitch in the minors again Monday.

Cameron Maybin was again not in the lineup with an injured left wrist. He has been out of the lineup since Aug. 28, though the Yankees have not identified the exact injury. Boone said on Saturday that it’s something Maybin may have to have surgery on following the season.

Gio Urshela is eligible to come off the IL on Sunday from a strained groin and Boone said he expects the third baseman to be active for the game, but not necessarily as a starter.

Luke Voit batted eighth in the lineup for a second straight day Saturday. The first baseman entered Saturday just 4-for-20 since his return from a sports hernia, but said he thought he was ready to turn a corner.

“I’m just missing the fastball right now,’’ Voit said. “I feel I’m right there. I found something with my stance on video and I think that should help. I have 20 games left to get right.’’

He went out and hit a booming double to center in the eighth inning, just his second extra-base hit since Voit’s been back.

“We want him getting that confidence and swagger back and locked in at the plate where he’s having those ‘grind it out’ at-bats,’’ Boone said.

Masahiro Tanaka makes the start Sunday, his first time pitching at Fenway since his 12-run, 3¹/₃-inning nightmare in July. He’s pitched well in four of his past five starts.

Thairo Estrada (right hamstring) had his rehab stint moved to Triple-A Scranton/Wilkes-Barre on Saturday after getting three hits in his first game back with Double-A Trenton on Friday.