Mastrobuoni is out of the lineup for Wednesday's game against the Reds.
Mastrobuoni had cracked the lineup in each of the Mariners' previous four games against right-handed starting pitchers, but he'll head to the bench Wednesday as the Reds send righty Nick Martinez to the hill. With Jorge Polanco limited to designated-hitter duties while he tends to a side injury, the Mariners could mix and match with Mastrobuoni, Ben Williamson (who is starting Wednesday) and Dylan Moore at third base rather than settling on a primary replacement.