O'Day, who was placed on the 60-day DL in late April following surgery to repair a partial tear of the labrum in his left hip, was 1-0 with a 3.68 ERA in six rehab outings with Double-A Frisco and Triple-A Round Rock. He had one walk and struck out 13 of the 29 batters he faced. His last appearance was Thursday in Round Rock, when he gave up two runs on three hits in two innings with five strikeouts and no walks.
Before his injury, O'Day was 0-1 with a 2.45 ERA in eight relief appearances with the Rangers in 2011. The hip not only gave him pain sometimes when he pitched, but also forced him to alter his mechanics as he tried to pitch through it. He said Friday that he's doesn't feel any pain and has improved his mechanics.
"I was putting my pitches where I needed to down there," O'Day said Friday. "The problem when I was hurting was that I wasn't consistent because I wasn't sure when it was going to hurt. My delivery was off. Now it's much better."
Kirkman is 1-1 with a 7.33 ERA in 11 relief outings for the Rangers in two stints this season. He allowed three runs in 1 1/3 innings on Saturday in the club's 15-5 win over Florida.
The Rangers have a full 40-man roster after this transaction.