Swarmer was optioned to Triple-A Iowa on Wednesday, Jordan Bastian of MLB.com reports.
Swarmer shifted to a relief role in late June and allowed six runs (three earned) on 10 hits and 10 walks while striking out 12 in 9.1 innings over six appearances out of the bullpen. However, he'll head to the minors after Daniel Norris (finger) was reinstated from the injured list Wednesday.