The Baltimore Orioles activated outfielder Heston Kjerstad and right-handed reliever Jacob Webb from the injured list before Sunday's game at the Detroit Tigers.
In corresponding moves, Baltimore designated left-hander Cole Irvin and infielder Nick Maton for assignment.
Kjerstad, 25, the No. 2 overall pick of the Orioles in the 2020 draft, was in Sunday's starting lineup batting fourth as the designated hitter. He entered Sunday hitting .261 with three home runs and 12 RBIs in 28 games this season.
He was hit in the head with a pitch July 13 and went on the injured list Aug. 7 (retroactive to Aug. 1) due to concussion symptoms. He hit .333 with a double, a run, three walks and three RBIs in six rehab games between Class-A Aberdeen and Double-A Bowie.
Webb, 31, had been on the injured list for more than a month with right elbow inflammation but is coming off three straight scoreless rehab outings at Triple-A Norfolk. This season, he is 1-5 with a 3.08 ERA in 53 relief appearances.
Irvin, 30, is 6-5 with a 4.86 ERA in 25 games (16 starts) this season.
Maton, 27, is hitless in five games this season with the Orioles.