NEW YORK -- The New York Yankees, with two-plus weeks left in the regular season, have a problem most teams would love: six healthy capable starting pitchers for five spots.

Last week, they solved it by bumping Nestor Cortes to the bullpen before rolling with a six-man rotation for the next turn. The plan was always to return to a five-man group after this week. This time, however, Cortes won't be the odd man out. It will be Marcus Stroman, manager Aaron Boone announced Friday.

Boone said Stroman, who has logged all his 148 innings this season as a starter, will be available out of the bullpen Sunday against Boston on regular rest five days after his start Tuesday against the Kansas City Royals.

Boone said "nothing is permanent" but hinted the Yankees would keep a five-man rotation for the next two turns. He said whether Stroman would stay in the bullpen for both turns -- if the Yankees stick with a five-man rotation -- hadn't been decided.

"I would say it's kind of fluid," Boone said. "But it's how I view it now."

The Yankees signed the veteran Stroman to a two-year, $37 million contract with a vesting option for 2026. He has logged a 4.07 ERA in 28 starts without a trip to the injured list, though the Yankees pushed a start back last month to allow for him to work on his mechanics after two dreadful outings. He had a 3.29 ERA in 17 starts through June 28, but in keeping with his second-half struggles in recent years, he has posted a 5.47 ERA over his past 11 outings.

The right-hander held the Royals to three runs over 5 innings Tuesday after the Texas Rangers roughed him up for five runs across 3 innings Sept. 4.

"He's one of the reasons we're here," Boone said. "He's gone to the post for us. Taken all his starts. Won a lot of ballgames for us. I think one of the reasons we have the chance to get to the postseason is some of the consistency of our starting pitching. And on balance, he's done a really good job for us.

"And as I told him, one of the reasons that we're in this position now. I feel like all of our starters have done a good job of giving us a chance to win a lot of ballgames. It starts with them and he's been right in the middle of all that."

Stroman has made eight relief appearances totaling 13 innings over his 10-year major league career. He last pitched as a reliever a year ago, making two relief appearances for the Chicago Cubs last September. He threw two scoreless innings in his first outing before giving up an unearned run in extra innings the next day.

Boone said he informed Stroman on Thursday he was returning to the bullpen.

"Stro's been so good for us and so good in the room," Boone said. "He's all about that team in there and all about the guys in there. So [his] message to me is, 'Whatever you need and I'll be ready to go.' I think he just wants to be part of a winner. And as much as we've enjoyed him being here with us and becoming a really important part of our room, that room has really loved him back. He's been a real joy for me to get to manage, frankly."

Cortes was the other obvious candidate for the demotion. The left-hander said he didn't know if he would return to the bullpen after limiting the Red Sox to one run over five innings Thursday.

The start came after he tossed 4 scoreless innings out of the bullpen against the Cubs on Sept. 7. After the relief appearance, Cortes admitted he was "upset" with the team's decision to move him to the bullpen, calling himself the team's "workhouse" this season.

"I'm just trying to go out there and throw up as many zeroes as I can," Cortes said Thursday night. "I know last week I might have come off like I was asking for too much, but I got my point across, and at the end of the day, I'm going to do whatever this team needs for me to do to win."

That could eventually mean pitching out of the bullpen again -- either in September or in October when playoff rotations shrink to three or four starters.