Michael Wacha's start pushed back

ST. LOUIS -- Michael Wacha is getting a break. The Cardinals and the pitcher agree he's struggled.

"He wasn't necessarily overly excited about how the ball was coming out of his hand," manager Mike Matheny said Friday after announcing the 23-year-old right-hander will be pushed back in the rotation. "So what do you do? You stick to the original plan, and we just stopped."

Rookie left-hander Marco Gonzales, who has backed up Wacha's two abbreviated starts, gets the start instead on Sunday.

Matheny said Wacha hasn't looked right since returning from a right shoulder stress reaction, an injury that sidelined him nearly two months. The Cardinals had been trying to build up Wacha's pitch count since he was activated from the 15-day disabled list in early September, and Matheny said he wasn't sure when the right-hander will pitch next.

The Cardinals have a day off Monday, and Matheny said he hasn't set the rotation after that.

Wacha threw in the bullpen Thursday and as in his September starts had trouble locating his fastball.

"It doesn't feel quite right and doesn't look right," Matheny said. "We're asking a guy to come into a September situation when we're in the hunt and expect a guy to be sharp with all of his pitches.

"It's not uncommon that they wouldn't feel sharp or right."

Matheny said it was premature to speculate about Wacha's availability for the postseason. The defending NL champions had a 2½-game lead in the Central with 17 games remaining.

Wacha allowed five earned runs and walked three in four innings his last start. As a rookie he was the NL Championship Series MVP, and he's 5-6 this year with a 3.14 ERA in 17 starts.

Gonzales was a first-round draft pick in 2013, a year after Wacha was taken 19th overall. The lefty is 2-2 with a 5.01 ERA but in his past two starts has permitted two runs in 10⅔ innings.