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6/23/2014 1:03 P.M. ET

Wacha, Garcia head to DL with shoulder issues

Righty has stress reaction, timetable unclear; lefty to begin rehab program

ST. LOUIS -- A Cardinals rotation that boasts the league's lowest ERA was dealt a significant blow on Sunday, when it was determined that both right-hander Michael Wacha and left-hander Jaime Garcia will be out indefinitely with shoulder injuries.

General manager John Mozeliak delivered the news shortly after spot starter Carlos Martinez helped the Cardinals to a 5-3 win over the Phillies. It was thought to be the final start for Martinez before he would shift back into the bullpen. Instead he, along with another fill-in starter, will be needed in the rotation until further notice.

Wacha's injury, described by Mozeliak as a stress reaction in his right shoulder, came as a surprise to the Cards, who were expecting more routine findings from a CT scan and an MRI performed earlier this week. The organization received the results on Saturday, and after Wacha continued to feel tightness when trying to throw on Sunday, decided he needed to be shut down for at least a few weeks.

Mozeliak did not have a timetable for how long the Cardinals' No. 2 starter might be out.

"He has been dealing with a little bit of shoulder irritation going back [four to five starts]," Mozeliak said. "Up to this point, we always thought it was manageable. This last start he missed, we did it just to give him some rest, because as we said all along, we're trying to bank some innings so come September and October, he'd be available, being a young pitcher. It's disappointing to learn of this, but obviously, he is too young and too valuable to take risks with."

Wacha, 5-5 with a 2.79 ERA this season, has allowed more than three runs in only one of his 15 starts. He has pitched at least six innings in 12 of them.

Garcia's injury is a little less shocking, as he has been dealing with discomfort in his shoulder for parts of the past three seasons. His terse answers to questions about his performance and health after pitching on Friday further hinted at a physical ailment.

Garcia underwent surgery in May 2013 to repair a labrum tear in the shoulder and missed the rest of the season. He had a setback this spring, too, which cost him the first seven weeks of the season. He was unavailable for comment on Sunday, though Mozeliak said it was his understanding "that his last couple [of starts], this is something that has been bothering him."

Garcia could not finish his normal between-starts bullpen session on Sunday.

There is also no timetable for Garcia's return, though he'll begin a rehab program immediately. Yet it is Wacha's injury that comes with more questions, since it is not commonly found in Major League pitchers. The injury does not require surgery, and the MRI did not reveal a fracture, but continuing to pitch could have led to one.

"I had taken off a couple days from throwing, and going into today, [I was] hoping it would start to feel a little bit better. It was still real tight," Wacha said. "It just takes a little bit longer to warm up and get loose. Just a little discomfort and something I'm not used to."

D-backs pitcher Brandon McCarthy is one possible comparison for the Cards to use in determining how to move forward. McCarthy has had recurring stress reactions in his pitching shoulder, and those have cost him several starts over several seasons.

"We'll certainly do our research between now and the next couple of days to do a protocol for his rehab," Mozeliak said.

With two of their starters suddenly on the DL, the Cardinals have the chore of patchworking their rotation. Martinez will remain in place and on schedule to pitch on Friday. The Cards will need someone to start in Garcia's spot on Wednesday.

The Cardinals fortified their bullpen and bench by recalling reliever Eric Fornataro and infielder Pete Kozma upon making the two DL moves official on Monday. The Cards had been playing with a four-man bench for the past week.

The club can then make another roster move after Tuesday's game to summon a starter for Wednesday, or could chose to cover the game with several relievers.

If the Cardinals look to the Minors for help, Triple-A's Tyler Lyons, Angel Castro and Zack Petrick would all be rested enough to start on Wednesday. There is also lefty Marco Gonzales in Double-A to consider. Gonzales, the organization's top pick in the 2013 First-Year Player Draft, has been pitching as well as anyone in the system and has plenty of experience playing in altitude.

Gonzales, whose father is a pitching coach in the Rockies' system, won four state championships pitching for a Fort Collins, Colo., high school.

Whomever the Cardinals choose is likely to be just a placeholder while they await Joe Kelly's return. Kelly, who threw an extended bullpen at Busch Stadium on Sunday, will begin his rehab assignment with a start for Triple-A Memphis on Friday. The Cards intend to have him throw 40 to 60 pitches in the outing.

Kelly, who has missed more than two months recovering from a strained left hamstring, will need to make at least two Minor League starts before rejoining the rotation.

"It's concerning. We really don't know what's coming," Mozeliak said of the suddenly blurred rotation picture. "You're putting two pitchers on the DL today. I'm not in a position where I'll know when they're return or how they'll return or the effectiveness of how they'll return. Joe Kelly, who we believe to relatively close in what we know, still has to check those boxes.

"It does leave us in a little bit of a gray area. Now, two weeks from now, a month from now, we may feel pretty good about where we are. But as I sit here today, I don't know that answer."

Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.