Capps fell to 0-3 with a 4.09 ERA in 11 non-save appearances, with all three losses coming at home.
"My mindset is not any different with a tie game or a lead or anything like that," Capps said. "I don't know for whatever reason, and a couple times at this park, I've pitched in tie games and it hasn't worked out. But there's been some times where it has."
Capps, pitching with the game tied in the ninth, served up the two-run blast on a 2-2 fastball with two outs. It came after he gave up a leadoff double to Corey Hart.
Capps said that in hindsight he would have thrown a slider to Maldonado on that pitch, but went with the fastball instead and paid for it.
"I was looking for a slider earlier in the count and then he started pounding the fastball," Maldonado said. "So that's what you want."
It spoiled an impressive night from Plouffe, who has been on fire in June, as he leads the Majors in homers with nine in 11 games. Plouffe, who was celebrating his 26th birthday, has also homered in six of his last seven games with seven blasts over that span.
"He's on the ball," Twins manager Ron Gardenhire said. "He's fun to watch. You see guys get on hitting streaks, but it's not too often you see a guy almost every time he puts a good swing on the ball it goes in the seats. That's what he seems to be doing right now."
Plouffe helped back left-hander Francisco Liriano, who allowed just one hit over six innings. But that hit was a costly one, as Ryan Braun broke up his no-hit bid with a three-run homer with one out in the sixth after he walked Edwin Maysonet and Carlos Gomez.
Liriano was able to bounce back and get out of the inning without any further damage and allowed just those three runs on one hit over six innings.
"We gave up two big home runs -- a three-runner and then a two-run runner there -- and they ended up costing us pretty good," Gardenhire said. "Frankie threw the ball really well but just had that one bad inning. Walked a couple to get in a little jam there and, of course, Braun is a great hitter and drove one out of the ballpark."
Plouffe opened the scoring for the Twins with a solo shot in the fifth off right-hander Yovani Gallardo. Brian Dozier followed with a single and advanced to third on a single by Drew Butera on a hit-and-run before scoring on a bloop single by Alexi Casila.
Plouffe hit his second homer in the next inning to tie the game at 3-3 and hand Liriano the no-decision. It marked Plouffe's first career multi-homer game and was his team-leading 14th homer of the season.
"He's swinging the bat well right now," Gallardo said. "Obviously he's hot. He's hitting every mistake, it seems like. The first home run, left a fastball up in the zone and he took advantage of it. And the second one, he fouled of some pretty good pitches. I guess when you're hot, you're hot."
But it wasn't enough for the Twins, who were held scoreless in the ninth by Brewers closer John Axford. The loss was the third straight for Minnesota, which had previously won 10 of 13 games.
"It was such back and forth," Axford said. "Liriano had a great start, mixing up all his pitches. He was doing a fantastic job keeping our guys on our toes. Luckily we came away with a few runs from him."