Cain (forearm) completed another bullpen session Tuesday, Alex Pavlovic of CSN Bay Area reports. The bullpen once again consisted of only fastballs, but Cain is now set to begin incorporating breaking balls in his next flat-ground session. That will mark an important step in Cain's recovery from a strained flexor tendon, but he will then have to start throwing breaking pitches off a mound before being cleared to face live hitters.