The Orioles have activated infielder Mark Reynolds off the disabled list and replaced him on the DL with right-handed reliever Stu Pomeranz.
Pomeranz, who had begun to provide some long-relief stability to the Orioles bullpen, strained his left oblique while warming up in the bullpen in Sunday's game against Kansas City.
Reynolds, who went on the DL with an oblique strain May 12, played two games of a minor league rehab assignment at Double-A Bowie, going 1-for-7 with four strikeouts.
Before going on the DL, Reynolds was hitting .191 with two homers and nine RBIs in 27 games with the Orioles. He's struggled defensively at third base, committing six errors in 15 games there, prompting manager Buck Showalter to use him at first and as a DH.
Pomeranz threw five scoreless innings for the Orioles before allowing his first big league runs Friday. Previously, he threw 23 1/3 scoreless innings in the minors this year at Triple-A Norfolk and Double-A Bowie. He currently owns an ERA of 3.00 (2 ER in 6 IP).