Catcher Hank Conger, one of the Angels' top three prospects, injured his right arm on a swing Monday and was put on the disabled list because of a right rotator-cuff strain.
The injury could limit the Angels even further as they try to add a player by the July 31 trade deadline. The Angels' system has little to offer teams looking to rebuild with minor-league prospects. Conger has had his right shoulder surgically repaired.
Angels general manager Tony Reagins said Conger's injury is tendinitis.
"It's something we're obviously monitoring, but right now it's day do tday," Reagins said.
Conger, 22, was batting .265 with five home runs and 27 RBIs for Triple-A Salt Lake.