Kennys Vargas has been the Twins' second-hottest hitter in May, his .366 average for the month only one point behind Torii Hunter's .367. But even Vargas doesn't think he's hitting like he should.

"I started hitting a couple base hits, but that's not what we're looking for," the 24-year-old designated hitter said after being told he is being optioned to Class AAA Rochester. "We're looking for [me to] produce. Produce means runs and RBIs. I'm DH, and you don't want me to hit a lot of [singles]."

Well, he was slugging .561 for the month, too, but point taken. Vargas, who went 0-for-1 as a pinch hitter in the Twins' 11-3 loss on Sunday, has not been the power source in the middle of the lineup the way he was last season, and manager Paul Molitor, who already moved him down to sixth or seventh in the batting order, believes the second-year slugger's mental approach has suffered as a result. Some time in a minor league lineup might lift some of the pressure, the manager decided.

"In simplest terms, when you're going well, it's kind of freedom of thought, freedom of swing. And right now [for Vargas], it's cluttered," Molitor said after breaking the news to the young Puerto Rican. He's overthinking each at-bat, sometimes deciding to be patient, sometimes aggressive. "The way they pitch to him, they get him to [swing] out of the zone fairly frequently. That's something to improve on, for him to be consistent up here."

The Twins won't need a designated hitter for the next two games, since they will be played under National League rules in Pittsburgh. And Molitor plans to spread out the DH workload among the rest of his regulars, for the time being, using it to rest players such as Hunter, Brian Dozier, Trevor Plouffe and Joe Mauer (each of whom has served as DH recently) while still getting them at-bats.

Eduardo Nunez, who has missed 17 games because of a strained left oblique, will be activated from the disabled list Tuesday to take Vargas' roster spot. The moves leaves the Twins with virtually zero power on their bench — Nunez, Chris Herrmann, Shane Robinson and Doug Bernier are their reserves, at least for now — as they head to PNC Park, where the need for pinch hitters for pitchers figures to come up.

Vargas was one of the Twins' best stories in an otherwise forgettable 2014 season, a surprise August call-up from Class AA who knocked in 16 runs during his first two weeks. But "his first time through, people paid attention," Molitor said. "They kind of learned what he can do, what his strengths were, and now they've made adjustments to him. Now he's going to have to counter them."

Vargas batted only .172 in April, with two extra-base hits in 64 at-bats, but with 21 strikeouts. Molitor benched him for three days late in the month, then left him out of the lineup four times in the past week. He's subtly criticized the slugger's habit of putting on a long-ball display during batting practice, rather than trying to keep his batting stroke short.

The problem isn't mechanical, Molitor said.

"It's more [about] what's going on in his head when he gets in the batter's box," the manager explained. "You've got a guy that potentially can be a very valuable part of the middle of your lineup and be a run producer. And through 100 at-bats, it really hasn't happened very much for him. So I think the best thing is for him to go down there and try to find a groove and relax a little bit and hopefully start to play a little better."

Even Vargas, who took the disappointing news stoically, sounded as if he agreed.

"They just told me to go back down to try to figure out how to get my rhythm back. I mean, I haven't been driving in a lot of runs," he said. "I'm OK. This is business. You have to adjust, keep your mind right and try to come back. I know I can come back quick. I just have to make an adjustment."