Sims was recalled from Triple-A Gwinnett on Saturday.
Sims made one appearance in a brief stint with the Braves earlier this season and it was a disaster. He lasted just one-third of an inning and gave up three runs on two hits and three walks. He's been solid in 12.1 innings for Gwinnett, though, striking out 16 batters while posting a 1.46 ERA. Max Fried was sent down to Triple-A to make room for him in the bullpen.