Rincon, 22, suffered an injury in minor league spring training camp and has not appeared in a game this season. In six seasons in the Padres' farm system, Rincon hit .285/.355/.422 in total 484 games. The infielder has never advanced beyond Double-A.
Grandal is coming off of serving a 50-game suspension for violating MLB's Joint Drug Prevention and Treatment Program. The 24-year-old catcher had a strong debut season for San Diego last year, hitting .297/.394/.469 with eight homers in 60 games. Grandal came over from the reds Reds along with right-hander Edinson Volquez, infielder Yonder Alonso, and right-hander Brad Boxberger in exchange for Mat Latos in December of 2011.