Castellanos is out of the lineup for Friday's game in Boston.
Castellanos' playing time early in his tenure with the Padres has been erratic. He did not start the first two games of the season, then started three straight and has now been back on the bench for two games in a row. Miguel Andujar is in the designated hitter spot for San Diego, and he and Castellanos are likely to continue sharing playing time in the slot.