"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."
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, 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.