Foltynewicz, a first-time All-Star last season, is 2-5 with a 6.37 ERA over 11 starts in 2019. He allowed eight runs on eight hits in four innings against the Washington Nationals on Saturday, though the Braves rallied for a 13-9 win.
"I've got a 7 ERA on a first-place team," Foltynewicz said after the game. "It's just tough. I'm battling every night. It's just tough. It's just the person I am. I'm going to wear that stuff on my sleeve, especially when things aren't going my way. It's just tough. It's all my fault, too."
Atlanta pitching coach Rick Kranitz said of the right-hander: "He's an All-Star, and he has great stuff. He just needs to go down, clear his head and relax and start making pitches."
The Braves recalled right-hander Chad Sobotka from Gwinnett in a corresponding move. Sobotka has an 8.25 ERA in 12 innings over 13 relief appearances for Atlanta this season.
Foltynewicz, 27, hasn't pitched past the sixth inning this year, with his ERA sitting above 5.00 all season.
He got a late start in 2019 after opening the season on the 10-day injured list with a right elbow bone spur, making his debut April 27.
The Associated Press contributed to this report.