Wacha carried a one-run lead and a no-hitter into the sixth inning but didn't make it out of the frame, while Frias lasted seven innings for the first time in his career and came away with his fourth win of the season as the Dodgers bested the Cardinals, 5-1, at Busch Stadium on Saturday night.
"Carlos was really throwing a lot of strikes," Dodgers manager Don Mattingly said. "It looked like he hit his spots."
Frias threw 55 of his 91 pitches for strikes, and the only run he allowed came in the first inning and was unearned.
The outing came on the heels of his worst game of the year, a loss to the Giants on May 24 in which Frias allowed 10 earned runs on 12 hits over four innings
"Last time he was all over the place," said Mattingly, who added that he was never worried that Frias' last start might carry over to Saturday. "Tonight, he seemed to be hitting his spots. He used his slider some. As the game went on, he started using his curveball. That's the key."
Frias credited catcher Yasmani Grandal for the successful start.
Grandal said the game plan was to pitch the Cardinals inside and to limit the off-speed pitches Frias threw in the early innings.
"I think Carlos has the ability to do that, so that's what we did," Grandal said. "We established the inner half and went away when we needed to. His slider was working real good."
David Cobb is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.