"I'm primarily a fastball-curveball guy," said Boshers, who has been working on a changeup. "My command [was good at Triple-A]. I was able to throw the ball where I wanted to and throw my breaking ball when I was behind in the count. That really helped my fastball get to where it needed to be."
Molitor said the move was made after Ricky Nolasco and Ervin Santana combined to go 6 1/3 innings over the last two games, causing the bullpen to be overworked. Molitor said he prefers a four-man bench with 13 position players, but that right now pitching depth is the priority.
"We need pitching, and we've talked about going to 13 for a while and it was expedited by our short starts the last couple days," Molitor said. "Buddy came over this winter and had a good spring, competing to the end. He has a nice left-handed mix. He attacks and gets left-handers out. He's done well down there and has been stretched out somewhat."
Mastroianni, who was 0-for-9 with two walks in seven games with the Twins since being called up on May 6, said he suffered the injury in Detroit last week. He said it continued to linger and that he felt it during early batting practice on Monday, causing him to shut it down on Tuesday. He's on the DL retroactive to Sunday, so he's eligible to be activated on June 6.
"I thought it wasn't really that big of a deal and played Saturday, and it felt OK," Mastroianni said. "There was some soreness, and it was a little tight. But Monday, I tried to swing and it didn't feel right. I couldn't really go. I tried to do what I could, but when you can't swing, it's just unfortunate. I've never had this before."
Perkins, meanwhile, is now eligible to return on June 10 after being placed on the 60-day with a strained left shoulder. It doesn't change his timeline, as he's set to resume his throwing program on Thursday after a setback last week, but he is roughly a week away from throwing off a mound. He'll also need a rehab assignment before returning.
"Pushing Glen to the 60-day from the 15 is probably not an issue in terms of timing," Molitor said. "Especially with him being pushed back roughly a week after suffering a repercussion last week while throwing."
Rhett Bollinger has covered the Twins for MLB.com since 2011. Read his blog, Bollinger Beat, follow him on Twitter @RhettBollinger and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.