Mastrobuoni is out of the lineup for Monday's game against the White Sox.
Mastrobuoni had started in each of the last four games at three different positions (second base, third base and right field), but he went just 1-for-11 with four strikeouts during that stretch. He'll be back on the bench Monday and should continue to serve as a utility player for Seattle, with his ability to play multiple outfield and infield spots enabling him to make a handful of starts per week.