Parra befuddled a Minnesota offense that had scored six or more runs eight times during its recent streak of 12 wins in 13 games.
"You're seeing a young Major League pitcher evolve into a pretty good Major League pitcher," manager Ned Yost said. "This is a guy that has been at the top of our prospect list for a long time, and now he has gotten to the big leagues and started to feel comfortable and have some success."
Parra (8-2, 3.95 ERA) is 6-0 with a 3.26 ERA since May 14. He knocked off baseball's hottest team on Saturday.
"I didn't think about it at all," Parra said of facing a streaking Twins team. "I know baseball well enough to know that on any given day, any team can win. I didn't think much about it. I just figured, follow [catcher] Jason [Kendall] and just trust my stuff."
Still, to hear Parra tell it, the lefty didn't have his best stuff against the Twins. He was frustrated at falling behind in counts and allowing four walks.
"I don't have to have my best stuff to do well as long as I am going out there and being aggressive with my stuff," Parra said.
Kendall calls Parra's stuff "dominating." The catcher said after the game that he wished Parra could reenact Bugs Bunny's skit of playing every position during a baseball contest. This way, Parra could catch himself.
"I wish he could throw the ball and go back and catch it and see how good he really is," Kendall said.
The Brewers pecked away at Twins starter Livan Hernandez early in the contest. Milwaukee took the lead in the first inning after Ryan Braun singled home Rickie Weeks. In the second, Mike Cameron doubled and advanced to third on the next at-bat when Hernandez's intended pick-off attempt ended up in shallow center field. Cameron scored on a Kendall groundout.
But Milwaukee stole most of Minnesota's hope in the third when it converted three walks and two doubles into three runs. Bill Hall's two-run double put the Brewers ahead, 5-0, in the third inning, and they never looked back.
This made Yost prophetic. Prior to the game, explaining why he had moved Russell Branyan to first base to give Hall the start at the third, Yost said: "I had a feeling that it would be a good night for Billy. So we'll find out if the feeling was right or wrong."
It was right.
The double was Hall's only hit, but his two RBIs gave Parra plenty of cushion.
"It's good for Billy. Billy's really been plugging hard and working hard and finally got a little something to show for it," Yost said.
Jason Kubel's ninth-inning home run off Brewers reliever Mitch Stetter prevented the shutout.
Prior to Saturday, Milwaukee had been the last team to defeat Minnesota. The Brewers beat the Twins, 4-2, on June 15 at Miller Park.
"That's a good team over there," Kendall said. "They play baseball the right way. It's fun to play against them in a sense. And at the other end, it's a battle every night."
In the home team's locker room, Minnesota was dealing with defeat for the first time in nearly two weeks.
"Tough night tonight," Twins manager Ron Gardenhire said. "They pretty much dominated us. [Parra] was really good. He changed speeds, he was effectively wild in the strike zone, in and out and, boy, his fastball was jumping. He had a decent breaking ball, a great changeup he threw when he was behind in the count. He really mixed it up on us and made it tough for our hitters."