Moehler has gone at least five innings in all six of his starts. He has allowed two runs or fewer in three of those and three earned runs in each of the other three. The Astros are now 4-2 in games started by Moehler, whose ERA since joining the rotation is 3.00.
"He did pretty good in all of them," Astros manager Cecil Cooper said. "We could have very easily won every one of them. You always hope you find a guy that steps up like that and we've always known that Brian throws strikes. Last year, we used him in a [multitude] of roles and he filled them well. He threw strikes and he's done the same thing in the starting role. We're going to just keep riding him as long as he's throwing well and pitching well."
Moehler's teammate Mark Loretta said the pitcher has been a key to the Astros' winning record.
"That's what winning teams need, is to get a guy you don't really expect to carry a load to come through like this, and that's what he's been for us," said Loretta, who went 4-for-4 in a spot start at shortstop.
Moehler (3-2) retired 12 of the first 14 batters he faced and allowed only one baserunner to reach third base. The right-hander struck out five and walked two.
"Moehler was the story," Cardinals manager Tony La Russa said. "We couldn't do anything with him. He didn't [throw] anything over the middle of the plate."
The Cardinals hit few balls hard, and their best chance at an extra-base hit died in Hunter Pence's glove in the sixth when he ran down a drive to right by Albert Pujols.
"He had command of all his pitches, kept us off balance," Cardinals center fielder Skip Schumaker said. "I've never seen him as a starter before. I was really impressed. His changeup was real good, his cutter he threw well and his fastball he threw for strike one a lot."
"He threw me a lot of split fingers in good spots," Cardinals right fielder Joe Mather said. "Tonight my eye wasn't as good as his pitches were. He hit a lot of nice spots, borderline pitches you hope they call balls."
Moehler said he felt like he could have pitched the eighth, but, at a season-high 93 pitches, he understood why Cooper made the change. He also said he's the same pitcher he's been since he first broke into the Major Leagues with Detroit in 1996.
"I haven't changed the way I've pitched since day one of my career," Moehler said. "I've always been a control guy for the most part, throw strikes and let our defense make the plays behind us. I'm not going to go out and strike out 10 guys, eight guys a night. I know what I'm capable of doing, throwing strikes and getting ahead of hitters."
Moehler struck out five, one shy of his season high.
"I pitch to contact, you know," he said. "I want guys to hit the ball. I don't want to sit out there and throw a lot of pitches. We've got a great defense."
Moehler's bid for his first complete game in eight years and first shutout in nearly nine years ended when he was replaced by Geoff Geary in the eighth inning.
By then the Astros had built a 5-0 lead off Looper (7-5).
"He was super," Cooper said. "I don't know how else you can say it. He just was outstanding tonight. He mixed his pitches. He even actually said he didn't feel really good about his fastball command early. He battled, he threw some cutters, he threw some sliders, changeups."
The Astros took advantage of a pair of Cardinals miscues in the fourth to score three unearned runs.
After Darin Erstad doubled and Looper hit Lance Berkman with a pitch, Carlos Lee followed with a grounder to short. Cardinals shortstop Cesar Izturis, who won a Gold Glove four years ago, threw the ball away attempting to force Berkman at second. Both runners scored and Lee made it all the way to third on the two-base error.
Lee came home on Geoff Blum's grounder to Pujols at first base, and was safe when Cardinals catcher Yadier Molina dropped Pujols' peg for an error.
Pence gave the Astros a 1-0 lead in the third when he lined Looper's first offering off the bullpen wall in right-center for an RBI double. Kazuo Matsui followed with a base hit to center to plate Pence for a 2-0 lead.
Blum hit his fourth homer of the season in the eighth to account for Houston's final run.