The loss by Milwaukee coupled with the Cubs win over St. Louis put the Brewers back into a first-place tie with the Chicago.
Armas tossed six innings of shutout ball, limiting the powerful Milwaukee lineup to three hits while upping his record to 4-5.
"Our starter pitched great," Pirates manager Jim Tracy said. "Obviously, the best game, in my opinion, that he's pitched. I think it's a combination of things -- it's been building to the point with what he's been working on with our pitching people, [Pitching coach Jim] Colborn and [Bullpen coach Bobby] Cuellar, and tonight, what you saw was a very confident guy that was very confident with his pitches... throwing a lot of strikes, using his fastball to both sides of the plate and between he and [Ronny] Paulino, the game plan that they had obviously they had them off stride."
"Ronny, he called a great game," Armas said. "I probably shook him off like three times. It feels good, but I think the most important thing is we won the game. That's the most important thing right now."
Carlos Villanueva took the loss, falling to 7-4. He lasted five innings and allowed two runs on five hits.
Armas and Villanueva traded goose eggs until the bottom of the fifth inning. Following a Nyjer Morgan double, McLouth crushed his 12th home run of the season over the grandstand in right field, staking the Pirates to a 2-0 lead.
McLouth's home run traveled an estimated 431 feet and bounced off a walkway into the Allegheny River. McLouth is the 17th player to reach the river, and it was the 22nd home run to reach the water -- the 21st on a bounce.
"It was a change up," McLouth said. "We kind of noticed from the bench that [Villanueva], who was pretty much dominating us up to that point, we noticed that he had been going offspeed with guys on base when he was behind in the count and he threw ball one. I kind of thought a changeup might be coming and guessed, and I guessed right."
McLouth has taken advantage of his opportunities and opened some eyes.
"He's become a player," Tracy said. "That's what he's done. He was a solid player last year, but he's become a very solid Major League player. Where he was at starting last year to where he's at right now -- he's a Major League player."
The home run was also the 1,000th home run in the seven-year history of PNC Park.
The Pirates tacked on two more runs in the sixth against Brewers reliever Matt Wise. After three singles loaded the bases with one out, pinch-hitter Josh Phelps bounced into an apparent inning-ending double play, but second baseman Rickie Weeks uncorked a wild throw to first. Phelps was credited with one RBI as two crossed the plate, giving
Pittsburgh a 4-0 lead.
The Pirates got to Milwaukee reliever Brian Shouse in the bottom of the seventh. Adam LaRoche delivered an RBI single to right before Shouse was replaced by right-hander Seth McClung, who surrendered an RBI single to Steven Pearce, an RBI double to Paulino and a sacrifice fly to Jack Wilson, as the Pirates cruised to an 8-0 advantage.
Pittsburgh closed out the scoring in the eighth inning as McLouth doubled and scampered home on a one-out double by LaRoche.
"It's evaluation time for them," Villanueva said of the free-swinging Pirates. "They don't have anything to play for, pennant-wise, but you certainly don't take them lightly. They have a pretty good team. They manufactured runs well today. You can't sleep on them."