Voth was optioned to Triple-A Fresno following Game 2 of Wednesday's doubleheader against the Phillies, Jesse Dougherty of The Washington Post reports.
Voth was called up as the 26th man for the twin bill and was in play to potentially serve as a spot starter, but he ended up not appearing in either contest. The 26-year-old returns to Fresno, where he has a 4.40 ERA, 1.36 WHIP and 68:15 K:BB over 61.1 innings.