The Royals optioned Barlow to Triple-A Omaha prior to the big club's 15-5 loss to the Blue Jays on Wednesday, MLB.com reports.
Barlow had served as the Royals' 26th man in a doubleheader Tuesday, but went unused out of the bullpen in both contests and continues to await his major-league debut. He'll likely resume working in a starting role upon returning to Omaha.