Burns walked the leadoff batter in the fourth inning and then misplayed a grounder back to the mound, leading to two Minnesota runs and an eventual 6-4 loss to the Twins at Miller Park.
"I just fell behind 3-1 too many times," said Burns, who was pulled from the game in the sixth inning after giving up a solo home run to Joe Crede. "When you fall behind 2-0, 3-0, you put yourself in a situation where you still have to try to make quality pitches, and I wasn't doing that."
Burns, who allowed four runs on six hits, walked three in 5 2/3 innings. The 30-year-old right-hander held the Twins hitless for the first three innings, but Minnesota got to Burns the second time through the lineup thanks to two mistakes of his own.
Minnesota's Denard Span walked to open the inning, and then Brendan Harris hit a soft grounder back to the pitcher's mound, which got by Burns for an infield single and left both runners safe. Joe Mauer flew out to center -- which would have been the inning's third out if a double play had been turned -- but Justin Morneau hit an RBI single for the game's first run.
Jason Kubel also singled to load the bases, and Burns walked the next batter, Michael Cuddyer, to extend the deficit.
"It's definitely disappointing, because it's a play that should have been made," said Burns, who ended up throwing 31 pitches in the fourth. "If it's made it's a whole different inning."
The Brewers scored three runs in the bottom of the sixth inning on a two-run home run by Casey McGehee and a solo shot by Prince Fielder to creep within a run of the Twins, but Minnesota answered with two in the next inning on RBI hits by Harris and Mauer.
"You always lose momentum when that happens, but you have to keep going up there and see what you can do, see if you can keep scoring runs," Fielder said of Minnesota's insurance runs. "You can't really dwell on that."
Twins starter Scott Baker (5-6) held the Brewers to three runs on four hits, striking out five, and Joe Nathan picked up his 17th save with a perfect ninth.
"He has to make his pitches good and pitch smart," Brewers manager Ken Macha said of Burns, "and I think if he would have limited his walks, it would have been a real good outing for him."
The loss concludes Interleague Play for the Brewers, which they struggled mightily in, finishing 5-10. Three of their wins came in a series sweep against Cleveland last week, with the other two wins against the White Sox and Twins.
Overall, the Brewers went 1-5 against Minnesota.
Macha said the stretch against more powerful American League lineups such as Cleveland, Detroit and Minnesota came at a time when his starting rotation was struggling to go deep in games, therefore also affecting the bullpen depth.
"We were scuffling at that times as far as getting the starters out there," Macha said, "so let's hope we get back into the National League and get our starters to go out there six, seven innings and not going into the bullpen in the sixth inning."
Ryan Braun, who homered in the eighth inning, said that NL teams are at a disadvantage on the road in Interleague Play, but when it comes down to it there's no excuse for the Brewers' mark.
"When we play Interleague games on the road, it's a big advantage for the American League, because they pay somebody to be a DH," Braun said. "They have a 30-homer, 100 RBI-type guy that they're paying to do that.
"When we play games here, it's just a matter of chance. At home, they shouldn't have an advantage over us. We're just not playing good baseball."
Cash Kruth is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.