The Angels optioned Silseth to Double-A Rocket City on Sunday.
The 22-year-old was recalled from Rocket City on June 28 and made two starts for the Angels, allowing seven earned runs on 11 hits with eight strikeouts and one walk over 8.1 innings between those contests. Between his two separate stints in the majors this season, Silseth has produced a 5.84 ERA and 1.46 WHIP in 24.2 innings spanning six starts.