Mastrobuoni is out of the lineup for Sunday's game against the Cardinals.
Though he's on the bench Sunday versus a southpaw (Jordan Montgomery), Mastrobuoni's opportunities to play against right-handed pitching may become more scarce now that Dansby Swanson is back from the injured list. With Swanson back in the fold, Christopher Morel is unlikely to see much time in the middle infield moving forward and could end up settling into an everyday role at third base, where Mastrobuoni had been occupying the strong side of a platoon with Patrick Wisdom.