When the Cubs were locked in as a team, their bullpen was a huge reason why.

Adbert Alzolay was closing things out in the 9th with Mark Leiter Jr. and Julian Merryweather serving in setup roles while Michael Fulmer bridged the gap from the starter to the high-leverage trio of arms.

As the Cubs enter their most crucial stretch of the season, they will be without half of those pitchers as both Alzolay and Fulmer are on the IL with forearm injuries.

Over the final 12 games of the season — all of which fall under the “must-win” category — David Ross has no choice but to piece together his bullpen.

Among the options Ross has to work with are three pitchers who actually started the season in the Opening Day rotation — Marcus Stroman, Drew Smyly and Hayden Wesneski.

“It’s unusual,” Jed Hoyer admitted as he spoke to the media before Tuesday night’s game. “But I think all in all, our pitching has been pretty solid and hopefully Stro can help a bullpen that has been a little bit banged up towards the end of the year.”

Stroman returned from the IL over the weekend in Arizona after missing six weeks with hip and rib injuries. He did not have enough time to ramp back up to a starter’s workload and was immediately thrust into back-to-back games out of the bullpen Friday and Saturday.

He looked good in both outings, striking out 4 while allowing 3 baserunners and an unearned run in 3 innings.

“You feel like it’s a real leverage arm we have in the bullpen,” Ross said. “He’s going to handle any moment fine. He has a ton of confidence. We can stick him at the back end, we could try to get multiple [innings] out of him if the situation arises. There’s a lot of confidence there.

“And there’s a real need with Fulmer and Adbert out. There’s just a real need in the bullpen for somebody that can handle those moments and give us a real weapon down there. It feels like he’s the right guy and willing to do whatever.”

The veteran right-hander went nearly a decade in between relief outings, spanning from his rookie season (2014) until last weekend.

There was a time not too long ago where the Cubs legitimately did not think Stroman would make it back at all this season with his mysterious rib injury. He was one of the game’s best pitchers for the first three months of the season, earning a trip to the All-Star Game and serving as a clear ace for this team.

Even if he’s not in the rotation, the Cubs are grateful to have Stroman back in some capacity.

“If you talk to him,” Ross said, “I think he’s on board with like, ‘Hey, I can help and I can lock down games and lock down leads and pitch in the biggest moments, if need be.’

“I don’t think his role is quite defined. But we’re going to use him in leverage and lean on him because he’s a really good pitcher.”

The Cubs aren’t shutting the door on Stroman making his way back into the rotation but with less than two weeks remaining on the schedule and every game carrying an added level of importance in the standings, they think it’s best he pitch in high-leverage innings out of the bullpen.

Part of that is by necessity. Without Alzolay or Fulmer, the Cubs bullpen is unsettled and roles are not defined.

Alzolay played long toss Tuesday and could return before the end of the season (he is eligible to come off the IL on Sept. 25). But in his absence, the Cubs will go with a closer by committee.

“I think we’ve got a couple of guys that feel tested in Merryweather and Leiter,” Ross said. “Boxberger just getting back, has thrown well. A veteran guy, probably not as much stuff as you would see out of a closer but has been on the back end of bullpens before. So the experience there. Drew’s thrown pretty darn good in his role.

“I think we’re best suited when everybody’s lined up really well, when we put Adbert in that that role. So that definitely did help. But I would venture to say all these guys are pretty much conditioned at this point to go in and get their outs.”

It is unknown if a pair of injured relievers — Brandon Hughes and Nick Burdi — will make it back to help the big-league bullpen this year. Both players are on the 60-day IL and currently rehabbing with Triple-A Iowa (Hughes threw Tuesday and Burdi is scheduled to pitch Wednesday).

Hughes broke out as a reliever last season and came into the year expected to be one of the team’s top bullpen arms. But a troublesome knee injury has cost him most of this season. He has been rehabbing throughout the month of September with Triple-A Iowa but has not had the results he or the Cubs would like though he did throw a scoreless inning Tuesday night.

Burdi has great stuff but only appeared in 3 games with the Cubs before he had to undergo an appendectomy in May and has been sidelined since.

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