The calendar says it's June. But Glen Perkins already is thinking about March.

That's the calculation, he said Friday, that caused him to abort his plan to eschew surgery, rest his left shoulder and hope that the pain would subside on its own. Realizing that the later he put off surgery, the more likely he still will be recovering at the start of next season, the Twins closer agreed this week to give up on 2016 and undergo an operation to repair his torn labrum.

"I rehabbed for two months. I don't want to keep rehabbing and start to push my timeline into next season. So the right time to do it is now," Perkins said Friday of the procedure, which hasn't been scheduled yet but likely will take place next week. "This gives me the best chance to be successful in the future, which at this point in the season is the right thing for me and the right thing for the team."

Perkins, 33, admitted shoulder surgery is far riskier than elbow surgery, and he supported the plan to wait. But after further testing found tears in both the front and back of his labrum, he decided enough time had gone by. Even surgeon Dr. Neal ElAttrache told him, "It's worth trying to rehab, because this is not a good surgery."

The specialist also found significant fraying of his rotator cuff, which will be "cleaned up" during the operation, Perkins said. But both injuries are the result of two decades of pitching, including 618 major league innings, so there's only so much that can be done.

Now, he says all he can do is work hard at rehab and hope to come out healthy.

"It's a degenerative thing. … There wasn't any certain day, there wasn't any certain time" the injury became apparent, he said. "I've thrown a lot of innings, I've thrown a lot of pitches. I've thrown a lot of pitches really hard."

Sano getting closer

Friday was supposed to be a light day in Miguel Sano's rehab. Fans in the right-center stands at Target Field might dispute that.

Sano, out since May 31 because of a hamstring strain, jumped in the batting cage and took a dozen or more swings, launching one ball into the left-field planters and another to the right-center seats.

"It was a pretty impressive show," General Manager Terry Ryan said.

But it's not Sano's bat that the Twins are concerned about.

"It's running, baserunning and so forth. Cutting," Ryan said. "He's making steady progress. As soon as you see him start doing some of that, we're getting closer."

Still, manager Paul Molitor said, the team is optimistic Sano is "maybe a tick ahead of what everyone originally thought. We're being cautious. Optimistically, he could go out [on a rehab assignment] within a week or so."

No room for Arcia

Oswaldo Arcia "was cordial [and] respectful" when informed Thursday that the Twins were designating him for assignment, Molitor said. But that doesn't mean it was easy.

"It was hard for me. I've known him for about seven years," Molitor said. "He seems like a good candidate for a clean slate."

And there figures to be at least some interest in him from another team, considering Arcia, 25, clubbed 33 home runs in his first two seasons, 2013-14.

"The message is out there. The other 29 teams know his status," said Ryan, who must trade, release or place Arcia on waivers over the next 10 days. If no team claims him, he could be outrighted to the minor leagues. "He has power, there's no denying it. But you have to pick and choose. You don't have an unlimited roster, that's the problem. … I don't like to give up on anybody."


• Outfielder Darin Mastroianni arrived in Rochester to begin a rehab assignment for his oblique strain.

• Righthander Trevor May's back has improved, and he hopes to throw off a mound sometime this weekend.