On the same day the Cardinals activated catcher Yadier Molina from the disabled list the club disclosed that backup catcher Tony Cruz had been playing several weeks with an ache in his left forearm that the team learned Monday was a stress fracture. The Cardinals placed Cruz on the 15-day disabled list to allow the injury to heal and optioned infielder Jermaine Curtis to Class AAA Memphis. Molina (knee) and Shane Robinson (shoulder) returned from the DL to take the open spots on the active roster. “When Yadi got injured (Cruz’s) workload went up significantly and unfortunately the forearm was not responding to where we thought it was getting better” general manager John Mozeliak said. “They thought the best thing for him was to shut down from swinging for at least seven to 10 days so that’s what we’re going to do.” Cruz said he was told to rest for 10 days. Cruz said the injury to his forearm was not caused by an event but rather developed over time. He has worn a compression sleeve on the arm for more than a month to help with the pain. He also limited his swings in recent weeks because of soreness. On Monday he went for an MRI scan and CAT-scan of the forearm. That exam revealed a stress fracture – Mozeliak called it a “microfracture” – in the middle of the forearm. Cruz said the physician recommended he “shut it down” and told him Monday that if he kept playing there was a chance the fracture would increase in severity. Cruz started Tuesday and Wednesday at catcher. “There was a chance of an actual break” Cruz said. “That was the risk I was taking.” Said Matheny: “We were told he’d be OK to play as long as we were real careful and we were aware of what was going on in there. We were careful.” Cruz did not take full batting practice either day and caught a total of 17 innings with six at-bats. He started 11 of the team’s 14 games while Molina was on the DL. It’s possible that Cruz will remain on the disabled list until Sept. 1 when rosters are allowed to expand beyond the current 25-man limit. Cruz going on the DL allowed the Cardinals to add Molina and keep veteran Rob Johnson on the active roster so that they’ll have three catchers available during September. Johnson would have to pass through waivers to return to Memphis and the Cardinals believed several weeks ago that another team would have grabbed Johnson if given the chance.