Atlanta designated De Los Santos for assignment Wednesday.
The transaction clears a spot on the 26-man active roster and 40-man roster for right-hander Tyler Kinley, who was acquired in a trade with the Rockies. De Los Santos has posted a 4.53 ERA and 38:18 K:BB over 43.2 innings for Atlanta this season. He could clear waivers, and if he does, he would have the ability to elect free agency.