Molina suffered a Grade 2 strain in his left quad during New York's 8-6 loss to Tampa Bay on Thursday. The veteran was filling in for Jorge Posada, who was placed on the DL earlier this week with a hamstring injury, and there is no immediate timetable for his return.
"He's on the 15-day DL, and hopefully that's all it is," manager Joe Girardi said. "Strains and quads and hammies can be fickle. We don't know how guys are going to come back."
The two catchers on the Yankees roster are now Cash and Francisco Cervelli, who had been called up from Double-A Trenton to replace Posada. Cervelli caught CC Sabathia on Friday and Cash said that he would catch starters' side sessions in the bullpen to help familiarize himself.
"It's not something you draw up, that's for sure," Girardi said. "But I believe that Cervelli and Cash have the experience to do this. If you watch them catch, they have an idea of what they're doing there and we have an experienced pitching staff."
Cash has played seven games for Scranton/Wilkes-Barre, going 9-for-18 despite a stint on the disabled list for a jammed right shoulder. A member of last year's American League Wild Card-winning Red Sox, Cash said that he signed a Minor League contract with the Yankees in part because of Posada's right shoulder surgery.
"You don't want to bet against a guy, but I think with the opportunities that were not out there on the free agent market, this appeared to be a good one," Cash said. "They had two veteran catchers here, but one was coming back from major injuries. I'd rather be [here] than going to a team that has two young guys and healthy. That can make it tough sometimes."
Right-hander Mark Melancon was also sent out to make room for Alex Rodriguez on the active roster, with right-hander Steven Jackson designated for assignment to clear room on the Yankees' 40-man roster for Cash.
With the activation of A-Rod from the disabled list, the Yankees will continue to carry both Angel Berroa and Ramiro Pena -- at least for one night. Girardi said that the roster would be re-evaluated depending on the Yankees' confidence in Rodriguez to play full games.
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.