Patrick Sandoval suffered a back injury and had to be placed on the IL Wednesday, the Angels PR team said.
Sandoval, 24, pitched 4.2 innings, throwing 83 pitches, in his most recent start on Friday, August 13 against the Houston Astros.
He had been a bright spot this season on a quickly-depleting young Angels rotation core. In 87 innings, he pitched to the tune of a 3.62 ERA and a 1.21 WHIP and was a top pitcher in preventing hard contact and getting whiffs.
José Quintana will start for the Angels tomorrow.