As Chicago Cubs reliever Brad Boxberger goes on the IL, a largely unproven bullpen continues to be tested

HOUSTON — The Chicago Cubs bullpen the last two years was built around proven veterans for high-leverage, late-inning spots.

Craig Kimbrel and David Robertson allowed manager David Ross to work in reverse when deploying his relievers in 2021 and 2022 — at least in the first half of both seasons until the Cubs traded away their top relievers. They haven’t been able to utilize the bullpen in the same way to start this season. Michael Fulmer and Brad Boxberger haven’t been the shutdown arms Ross can reliably count on in key spots.

And now Boxberger is sidelined, landing on the 15-day injured list Monday with a right forearm strain. Boxberger will rest his arm for a couple of days, and if it isn’t feeling better, he will head to Chicago for further examination. The seriousness of Boxberger’s injury won’t be known until later this week, though forearm strains can lead to Tommy John surgery.

“He’s had such a long, good career, pitching with seventh-inning leads and getting a lot of holds, and he hasn’t gotten in that rhythm yet,” president of baseball operations Jed Hoyer said. “He’s not a guy that’s throwing 97, so command and execution is really important and he hasn’t gotten quite there yet.”

Boxberger, who turns 35 next week, has allowed nine runs and 13 hits in 14⅔ innings over 17 games. Ross said Boxberger had “some groin stuff” going on, and then mechanical issues cropped up. Once those were ironed out, the arm issue arose. It’s hard to say whether the groin problem and subsequent mechanical problems led to Boxberger’s sore arm.

“You try to pitch not 100% and do the best you can and you get some bad habits, and we fix the bad habits and then other things pop up,” Ross said. “So this will give him a nice break. Get back to where he needs to be consistent with his mechanics and with his health and hopefully come back and be the best version of himself.”

The Cubs recalled right-hander Jeremiah Estrada to replace Boxberger. They also optioned right-hander Hayden Wesneski to Triple-A Iowa and selected right-hander Nick Burdi from Iowa. Adrian Sampson was transferred to the 60-day IL to create a 40-man roster spot for Burdi.

Back-to-back blowout losses in Minnesota that forced the pen to cover half the innings required the front office to bring in reinforcements ahead of Monday’s series opener against the Houston Astros at Minute Maid Park. The absence of established back-end options has forced Ross to go with a matchup approach and try to find the right stretch of the lineup for each reliever.

“He’s done a really good job of trying to piece it together,” Hoyer said. “But we haven’t had anyone that’s stepped up to lock down the ninth inning, and as a result it’s pitchers based on a pocket of hitters and that can be hard sometimes.”

Fulmer surrendered a go-ahead, two-out, two-run homer to Alex Bregman in the seventh Monday that stood as the decisive runs in the Cubs’ 6-4 loss to the Astros. Brandon Hughes (one-third of an inning) and Adbert Alzolay (one inning) put up zeroes in relief of starter Jameson Taillon, who allowed four runs and seven hits in 4⅔ innings. All of the runs against Taillon came in the first.

“We don’t really have any real roles down there quite yet,” Ross said. “They’re out getters and everybody relying on that. ... If we can line those things up, but we don’t always get the matchup we want.

“We’ve got to continue to maximize their strengths and rely on them to compete the best way they can.”

Optioning Wesneski doesn’t mean Kyle Hendricks will come off the IL this week to take his rotation spot. With days off Thursday and Monday, the Cubs can utilize a four-man rotation for a stretch.

Hendricks likely will join the team to throw a bullpen session and then is expected to make his next start with Iowa. Hoyer planned to sit down with the coaching staff after Monday’s game to map out the plan.

“Sometimes during the course of the year,” Hoyer said, “you get into a situation where you’re kind of playing a little bit night to night until you get an off day or until you get a good start when someone finally gives us seven and we can throw a couple of innings out of the bullpen and get a win.

“That’s when you can sort of reset, but until we can reset ... we’ll be going through that a little bit, playing catch-up from the weekend.”

Trey Mancini honored at Minute Maid Park

Trey Mancini isn’t sure yet where he will keep his new hardware.

Astros manager Dusty Baker presented Mancini with his 2022 World Series ring before Monday’s game. The Astros also aired a video tribute to the first baseman, who played 51 games for them after the Baltimore Orioles traded him at the deadline.

“I’m definitely going to make sure I keep tabs on it,” Mancini told the Tribune. “The last time I was here was during the parade, and winning the World Series, getting the experience of the parade, just that whole week of jubilation with a lot of good memories, you remember that.

“Not that you really need a reminder, but it does give a reminder of why we all play this game and how special it is to be part of a great team.”