"I said thank you to them," Rodriguez said. "I try to make good pitches, that's what I do."
Cardinals shortstop Brendan Ryan endured a second straight two-error game and his fielding miscue in the fourth helped the Astros score five unearned runs to go ahead 6-1. Jeff Keppinger's three-run double and Berkman's fourth homer of the season that glanced off the right-field foul pole came on consecutive pitches from Kyle Lohse (0-3).
"I was praying, leaning -- let the thing stay straight," Berkman said. "Anytime you can score runs early and let your guy relax a little bit, that's good."
The Astros totaled 12 runs in the left-hander's first six starts. Not that much would have helped Rodriguez after he gave up seven earned runs in 8 2/3 innings in a pair of losses to start May.
Rodriguez (2-4) allowed four earned runs on five hits in six innings. Manager Brad Mills preferred to savor the first five innings.
"He was pounding the zone with everything," Mills said. "He came out so aggressive and you could tell his demeanor was great."
Keppinger also singled and scored after a 2-for-20 slump and Berkman's homer was the first in 100 2/3 innings allowed by Cardinals starters at home. Berkman also matched a career best with four walks, the first three off Lohse.
Keppinger wore a hat shaped like a giant taco as he met with media, although he denied he'd been slumping.
"You're going to go through spells during the season where you feel good but you're just not making solid contact," Keppinger said. "That's kind of how it felt for me.
"I'm glad this was the game where I started to come through," he said.
Houston led 9-1 before Rodriguez (2-4) said his arm motion got out of whack. The Astros still had plenty to win their third straight and saddle St. Louis with only its third series loss out of 11 this season and for Rodriguez to end a seven-game road losing streak over 10 starts.
It's also the Astros' first series win at 5-year-old Busch Stadium and their first of three or more games in St. Louis since taking two of three Sept. 14-16, 2004.
Rodriguez added a single and sacrifice fly for his first RBI of the season and is 5-for-14 at the plate.
The Cardinals' rotation entered with a major league-leading 2.50 ERA and Lohse is the only starter without a victory -- he also has a 5.68 ERA. He allowed nine runs, a career high.
"I just wasn't very good all around," Lohse said. "I left a couple up, left a lot up, and every time I left it up they hurt."
Defense had kept Ryan in the St. Louis lineup, with great range and only three errors the first 32 games. He was also 0-for-3, dropping his average to .173 after taking early batting practice.
Ryan noted both errors were difficult plays. The ball glanced off his glove on a soft sinking liner by Humberto Quintero gave the Astros two on to start the eighth.
"I thought I was going to catch it at my belt at the minimum," Ryan said. "Next thing I knew I was trying to make a catch at my shoetops. That's two tough ones, I don't do anything different, really."
After both games, manager Tony La Russa offered comforting words.
"I just know he's a really good defensive player," La Russa said. "This happens, hang with it."
Matt Lindstrom got the last out for his eighth save in eight tries, allowing an RBI double to Pujols before Matt Holliday lined out. Lindstrom has 20 straight saves sinec April 28, 2009, and hasn't allowed a run in his last 10 appearances covering 10 1/3 innings.
The Astros fielded their major league-leading 32nd different lineup. The Cardinals aren't too far behind with 28. ... Pedro Feliz had an infield hit in the second for his 1,000th career hit, ending an 0-for-9 drought, and singled in the fourth. ... Michael Bourn had two hits and is 10-for-21 against the Cardinals. ... The Astros are 11-3 when scoring four or more runs and 1-18 otherwise.