McGowan (undisclosed) was placed on the disabled list Monday at Triple-A Las Vegas, Betsy Helfand of The Las Vegas Review Journal reports.
McGowan will hit the disabled list after appearing in eight games out of the bullpen for Las Vegas. He's struggled significantly this season, accruing a 4.70 ERA and 1.66 WHIP across 15.1 innings. It's unclear how long the 26-year-old right-hander will remain on the shelf.