Slaten struck out one over a scoreless inning in the second game of Monday's doubleheader against Toronto.
Slaten, who was activated from the 15-day injured list earlier in the day, made his first appearance for the Red Sox since July 7. He came on in the fourth inning and worked around an infield error. The Red Sox have felt Slaten's loss, and they hope the right-hander can stabilize what has been a shaky bullpen in the second half.