The Royals released Barlow on Thursday.
Barlow pitched in 36 games for the Athletics earlier this season before being cut loose in June. In 11 games with Triple-A Omaha, Barlow recorded a 5.65 ERA, 1.95 WHIP and 14:15 K:BB across 14.1 innings. The 33-year-old will likely have to settle for another minor-league deal elsewhere.