MINNEAPOLIS -- The Twins placed struggling left-handed reliever Adalberto Mejía on the 10-day injured list on Thursday with a right calf strain, and they selected the contract of right-hander Mike Morin from Triple-A Rochester, bringing the 40-man roster back up to 40 players.

According to Twins manager Rocco Baldelli, Mejia was doing a workout on Wednesday afternoon when he felt the strain in his leg, and he expects the 25-year-old southpaw to be sidelined for more than the minimum 10 days.

"It’s not an injury that we probably want to mess around with," Baldelli said. "We just want to give him an opportunity to heal up and see where we’re at at that point."

Mejia has struggled this season after he was moved to the bullpen following Spring Training, allowing 12 runs (11 earned) in 11 1/3 innings for an 8.74 ERA, with 11 strikeouts and nine walks. He last appeared in Tuesday night's 11-0 loss to the Astros, when he allowed a single and three walks -- including one with the bases loaded -- and was charged with four runs (three earned) in one-third of an inning.

Following that appearance, Baldelli spoke of the need for the coaching staff to get together with Mejia to figure out how to best unlock his upside and help him find consistency.

"There have been times where he gets to two strikes, and the pitches that he's able to throw with consistency, he just hasn't been able to get to at that point," Baldelli said. "And that's something where you can look at and say the promise is there, the ability is there, it's just having him take that next step."

Baldelli didn't rule out Mejia's transition to the bullpen as a possible contributing factor to the struggles early this season. Mejia has almost exclusively been a starter in professional baseball and was last used as a reliever for an extended period in Class A in 2012.

"It could be a big part of it," Baldelli said. "We've seen guys step right into that role and it just comes very easy to them. And we've seen many guys over the course of the years give it a go and there's just a different aspect to just going out there, and not just coming out of the bullpen, but coming into a game completely ready to go on the first pitch. That's a challenge."

Morin, who turns 28 on Friday, was signed to a Minor League contract during the offseason, but he has Major League experience in parts of five seasons, with a 4.66 ERA in 186 appearances for the Angels, Royals and Mariners from 2014-18. He had a 2.25 ERA with 12 strikeouts and three walks in 12 innings for Rochester this season.

"He’s a veteran guy who’s been around and understands that getting outs is the most important thing, and he has different ways of doing that," Baldelli said. "So he could find himself pitching in probably a variety of ways, but he could find himself pitching in some situations where he’s giving us some length, but also he could find himself pitching in some important spots, too."