The rotation reordering means that Carlos Martinez (Saturday) and Adam Wainwright (Sunday) will start this weekend.
"It's always been something that we thought was important, to try to bake in some rest, and at the quarter turn, I just think it makes sense to do that," general manager John Mozeliak said before Friday night's series opener. "We might not be afforded that opportunity again until the All-Star break. If you're always kicking the can down the road, you can end up being like, 'Uh oh. It's too late.' So I think anything you can bank now is smart."
Wacha, Mozeliak and manager Mike Matheny insisted that this decision was not dictated by any current concern. Wacha noted that he is feeling strong and was preparing to start on schedule until the Cardinals came to him a few days ago to announce their change in plans.
Wacha was limited to 138 innings in 2016 due to a stress reaction in his right shoulder. The same injury sidelined him for more than two months in 2014.
"I want to be a guy that's out there for 32 starts, and making every start," Wacha said. "But it's something they want to do and I've just got to be on board with it and use this time to get better, get stronger, and get ready for that next start."
Out on rehab
Third baseman Jhonny Peralta will join Triple-A Memphis this weekend to continue his rehab assignment after the Cardinals concluded that a three-day stint with Class A Advanced Palm Beach was not a demanding enough test.
Peralta, who is recovering from an upper respiratory infection, went 2-for-8 for Palm Beach. He returned to St. Louis earlier this week for further examination and went through pregame work with the Cardinals on Friday.
"For me, I'd like to see a little bit more robust rehab assignment -- have him play a position, have him take at-bats -- and then we'll have a better sense of where he is," Mozeliak said. "The energy level and some of the things that were concerning when we put him on the DL, it needs to be tested."
Right fielder Stephen Piscotty is also nearing a rehab assignment, though his is likely to be with Double-A Springfield. Piscotty, who went on the disabled list with a right hamstring strain last Friday, has resumed hitting, throwing and running.
"I feel the spot a little bit, but it's so much better than it was," Piscotty said. "[The recovery] is going really well."
The Cardinals are targeting Monday as a start date for Piscotty's rehab stint. If all goes well in Springfield, he could return from the DL for next weekend's series against the Giants.
Other injury news
• Tyler Lyons (right intercostal strain) will continue his rehab work with a start for Memphis on Monday. Lyons threw 35 pitches over 2 2/3 innings with Class A Peoria in a rehab appearance on Wednesday.
• Jose Martinez has been diagnosed with a Grade 2 groin strain and will likely be sidelined for at least a few more weeks. Mozeliak left the timetable intentionally ambiguous, saying only that the team wants Martinez to be patient with his rehab work.
• After not starting any of the team's six games on the road trip due to lingering soreness around his right lat muscle, Dexter Fowler returned to the lineup on Friday.
• Marco Gonzales is set to rejoin the Memphis rotation after a strong start for Palm Beach earlier this week. Gonzales is working his way back from Tommy John surgery, which he underwent in April 2016.
• Mozeliak said that John Gant (right groin strain) is pitching well in extended spring camp and is also likely to be added to the Memphis rotation soon.