Abad, 30, has been a solid addition to the bullpen, tossing 4 1/3 scoreless innings in five appearances this season. Abad, who was signed as a Minor League free agent in the offseason, has struck out four and walked two.
O'Rourke was the one of the final cuts in Spring Training, and got his first taste of the Majors last year, posting a 6.14 ERA in 28 outings. The 27-year-old struck out 24 and walked 15 in 22 innings.
Rhett Bollinger is a reporter for MLB.com. Read his blog, Bollinger Beat, follow him on Twitter @RhettBollinger and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.