The Guardians optioned Sandlin to Triple-A Columbus on Monday.
Cleveland's pitching staff now sits at 12 men -- one below the maximum amount imposed by MLB -- but Sandlin was sent to the minors to clear a spot on the 26-man active roster for right-hander Aaron Civale (thigh), who is on track to come off the 15-day injured list to start Tuesday's game in Minnesota. Sandlin had appeared in 19 games out of the Cleveland bullpen this season, compiling a 2.89 ERA, 1.61 WHIP and 18:13 K:BB across 18.2 innings.