"He said he went through six times where it kept on recurring, and one year it just never came back," Wacha said. "There is definitely some optimism looking forward there."
Wacha said McCarthy downplayed how much mechanical changes helped him get past the recurring issue.
The Cardinals' medical staff also has been working with Wacha to develop a new rehab strategy. Wacha recently visited a Chicago-area orthopedist for another opinion on how to best address the injury, and last week he underwent a bone-density scan.
The strengthening program that the Cardinals are creating, general manager John Mozeliak said, is being done with the intent of getting Wacha ready to return as a starter. Whether he'll be able to handle that workload is something that will be learned in time.
"I think the biggest thing for him is to have the confidence to know that this is something that's not going to be here moving forward," Mozeliak said. "I think everyone on the medical staff, and he included, feel like we have a good game plan."
Wacha hopes to resume playing catch by early next week and said he remains "very optimistic" that he will return this year. If he does, it would be in a bullpen capacity.
"I've been feeling good, and it's been healing up quick for me," Wacha said. "I'm definitely very positive about where I am and the future."
• Matt Adams (right shoulder inflammation) will begin a rehab assignment with Triple-A Memphis on Thursday. The Cardinals have not projected how long they expect that rehab assignment to last.
• Aledmys Diaz (right thumb fracture) returned to the infield on Wednesday to take more ground balls and work on his fielding technique with coaches David Bell and Bill Mueller. Diaz has not been cleared for other baseball activities.
• Brayan Pena (left knee inflammation) transferred his rehab assignment to the Gulf Coast League Cardinals and went 0-for-3 as a designated hitter on Tuesday. Pena has yet to catch in any of his four rehab appearances.
• Shortstop Allen Cordoba, ranked by MLB Pipeline as the Cardinals' 20th-best prospect, was named the Most Valuable Player in the GCL and was one of three Cardinals players to land on the GCL All-Star team. Cordoba, 19, ranks first in the GCL with a .342 batting average and .401 on-base percentage. Outfielder Bladimil Franco, 21, and left-hander David Oca, 20, were also recognized as All-Stars.
Jenifer Langosch has covered the Cardinals for MLB.com since 2012, and previously covered the Pirates from 2007-11. Read her blog, By Gosh, It's Langosch, follow her on Twitter @LangoschMLB, like her Facebook page Jenifer Langosch for Cardinals.com and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.