Hoffmann hasn't pitched since being optioned to Triple-A Reno on Aug. 20 while dealing with fatigue, Alex Weiner of ArizonaSports.com reports.
Reno hasn't yet placed Hoffmann on its injured list, so he could be back in action within a few days. Hoffmann has posted a 6.55 ERA and 2.00 WHIP over 11 innings in 10 appearances at the MLB level with the Royals and Diamondbacks this season.