The Blue Jays optioned Thornton to Triple-A Buffalo on Wednesday.
Toronto will swap Thornton out of its bullpen for another right-handed option in Casey Lawrence, who was called up from Triple-A in a corresponding move. After rejoining the Blue Jays on May 31, Thornton appeared in 16 games and turned in a 4.98 ERA and 1.34 WHIP across 21.2 innings.