"I felt good," Fien said. "I was pain-free. It was easy to get loose. That was the main thing. When I was here and I was a little injured, it took me a long time to get ready. But getting ready in 12-15 pitches is perfect for me. The velo was there and it was free and easy, which is what I wanted."
Fien, 31, was the club's top setup reliever each of the past two seasons, combining to post a 3.95 ERA with 124 strikeouts in 125 1/3 innings. He posted a 4.35 ERA with three strikeouts in 10 1/3 innings before going on the DL. He was plagued by the shoulder issue since his first outing of the year on April 9.
Fellow right-hander Blaine Boyer has taken over eighth-inning duties for the Twins, and he has been lights-out with a 2.28 ERA over 23 2/3 innings. Twins manager Paul Molitor said he'll ease Fien back into action with Boyer keeping his spot as the club's top setup reliever to closer Glen Perkins.
"When we get in there late with a chance to get outs in the latter third of a game, Casey would probably precede Boyer in the game," Molitor said. "I think that could change. We'll have to see how Casey is doing. But for now, I'm comfortable with Boyer out there getting outs in the eighth inning."
Fien said he's fine with whatever role Molitor has for him, and said he's excited to join a bullpen that has fared well this season, considering the club has only lost once all year when leading after the fifth inning.
"I just told him that whenever he calls my name, I'll be ready," Fien said. "I've always been a guy where that doesn't matter. It's about getting outs. And sometimes the most important outs are in the seventh or eighth inning."
Tonkin, meanwhile, had a 5.14 ERA with seven strikeouts and two walks in seven innings with the Twins. But he fared well coming into jams, as he allowed just three of 13 inherited runners to score.
"When you look at Michael Tonkin, he was here for almost exactly a month, and while all of his outings weren't great, when you think about the games we've won over the last few weeks, there's been times he's gotten really big outs," Molitor said. "So I let him know we saw that and that we know he's a guy we think can help us up here."
Rhett Bollinger is a reporter for MLB.com. 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.