The Yankees bullpen is down an arm, with Fernando Cruz sidelined with a shoulder injury and unavailable since his last appearance on Saturday.

Luke Weaver continues to compensate for their bullpen weaknesses, whether due to Cruz’s injury or stepping in as the closer for Devin Williams after the former Brewers closer struggled initially in The Bronx.

Wednesday, Weaver entered a tie game in the top of the ninth after Yerry de los Santos allowed a leadoff single to Sam Haggerty.

Weaver got both Wyatt Langford and Josh Jung to fly out to center field before he wrapped up the inning by throwing to second base to catch Haggerty, who was attempting to steal the bag.

That set up Jasson Domínguez’s game-winning homer with one out in the bottom of the ninth of a 4-3 win.

Aaron Boone called it a “good, gritty win, when we’re kind of short” in the bullpen. Not only are they without Cruz, but Ian Hamilton has struggled.

Jonathan Loáisiga is getting back into form, though he wasn’t at his sharpest Wednesday.

Weaver has allowed just one run in 20 appearances, covering 21 ²/₃ innings.

“He’s been outstanding,” Boone said of the right-hander. “He’s excelled at controlling the ball and placing it precisely where he intends. Some evenings, he’s been overpoweringly dynamic. Other times, he’s shown skill and savvy with the changeup. Ultimately, it’s about delivering the ball to the desired spot consistently.”

But as so many other relievers have shown, it’s not that simple.

He did on Tuesday, when Hamilton couldn’t finish the game, knocked out after a two-run homer, followed by a triple.

Then Weaver had to come in with one on and no one out Wednesday after Boone tried to get an extra out from de los Santos in the ninth.

As he’s shown often since taking over for Clay Holmes as closer for the final month of the regular season last year, Weaver has been undaunted.

On a night when they got five innings from reliever-turned-starter Ryan Yarbrough then needed five current relievers to finish it, Weaver was the stabilizing force at the end, as he earned his sixth save of the season.

The four saves he had last year were the first of his career, but he’s clearly comfortable at the end of games and can do it in a variety of ways.

His role may be even more important while Cruz is out, though Williams’ improved showing since being put into a setup role, as well as the return of Loáisiga and solid performances from Mark Leiter Jr. and Tim Hill have the Yankees set up well in the pen for the foreseeable future.