ST. LOUIS -- Michael Wacha will return to the rotation the next time the Cardinals need a fifth starter, president of baseball operations John Mozeliak told MLB.com.

Wacha earned another opportunity to start after allowing one run in 4 2/3 innings in Saturday’s 8-2 loss to the Astros. He entered the game after starter Daniel Ponce de Leon loaded the bases with three walks in the third.

It’s unclear when that opportunity will come, as the Cardinals have off-days on Monday and Friday that could potentially see them go to a four-man rotation until Aug. 7 against the Dodgers. Cardinals manager Mike Shildt said that will be discussed before announcing the rotation plans later this week.

Ponce de Leon replaced Wacha in the rotation after the All-Star break. But other than the rookie right-hander's start on July 12, Ponce de Leon has not been able to get past the fourth inning in any of his last three starts and Wacha has relieved him in the past two outings.

“It was a big outing for Michael,” Shildt said Sunday. “We [thought] about sending him back out or hitting for him. We were like, ‘Man, I like his stuff, the way it’s coming out.’ We thought sacrificing a potential out there was worth the two innings. Also wanted to stretch Michael out a little bit, see what that looks like. Bullpen’s been carrying a lot of the mail, so making sure we give some of those guys a blow down there. A win-win in a loss, and there is carryover to that.”

Wacha is 6-4 with a 5.15 ERA in 19 games (14 starts) this season. He was moved to the bullpen in early June to work on his velocity and command, but he was inconsistent when he returned to the rotation two weeks later. Ponce de Leon relieved Wacha in two games -- June 29 and July 4 -- before the roles were swapped.

For now, the roles are swapping again as the Cardinals continue to search for consistency in that fifth rotation spot, which could also potentially be filled as Wednesday’s 3 p.m. CT Trade Deadline looms.

“I wouldn’t say it’s concerning, the word I would use is frustrating,” Mozeliak said. “You would like someone to take it and run. Michael pitched early on well, so now he’s going to get another opportunity.”