"We need to give him a bit of a mental break here," Gardenhire said.
Perkins is still scheduled to make one more regular-season start on Saturday, Sept. 27, in the second game of a series against the Royals. Left-hander Francisco Liriano will start that series, and Baker is then set to pitch the final game of the season.
For now, Perkins will move to the bullpen. Gardenhire said the left-hander will be a relief option later this weekend if the Twins run into an emergency, but the club would prefer not to use him if possible.
"We're looking at an arm here that's had a lot of innings," Gardenhire said. "We don't want to go out and try to murder a guy in the bullpen."
The Twins' greatest concern recently with Perkins has been whether he is starting to wear down from too many innings. He's 0-1 with a 9.42 ERA in four September starts and hasn't pitched past the sixth in any of those outings.
The struggles have come at a time when Perkins has already recorded 179 1/3 innings, between the Majors and Minors, nearly 50 innings more than his career high for a season. He's also coming off an '07 season in which he threw just 48 innings due to a shoulder injury.
Perkins was asked after his start Thursday whether he felt fatigue was an issue.
"As far as my physical health goes, I feel good," Perkins said. "But maybe I'm trying a little too hard, pressing too much coming off a few bad outings, and not concentrating on making pitches."
Gardenhire hasn't eliminated the idea that fatigue might be a factor. But he agreed with Perkins that the problems he endured on Thursday were mostly a cause of trying to do too much with his pitches.
"I think with Perk right now, it looks like he is trying to pitch and not make a mistake," Gardenhire said. "When you pitch against what got you going in the first place, and that's attacking, you start making mistakes. I think he's trying to be too fine with his pitches instead of letting it fly. So we'll see what happens."