The Braves also activated infielder Gordon Beckham from the disabled list before Tuesday night's game against the Philadelphia Phillies. Outfielder Matt Tuiasosopo was designated for assignment after being with the team for one week.
Krol had a 4.38 ERA in 12 appearances at Gwinnett. He allowed only a .136 batting average against left-handed hitters, with 10 strikeouts and no walks in 6 1/3 innings.
Beckham missed 18 games with a strained left hamstring.