The hard-throwing Rodriguez was available out of the bullpen for the opener of a three-game series against the New York Mets. Cubs manager Dale Sveum said he planned to use the right-hander in a middle relief role at first and the team hopes to build up his endurance because he may be needed to pitch two innings at a time.
The 26-year-old was obtained Tuesday from Washington for minor league pitcher Ian Dickson after going 0-1 with 4.00 ERA in 17 appearances covering 18 innings this season. He struck out 11 and walked 16.
Control is often the problem for Rodriguez, who has a 4.23 ERA and 11 saves in five major league seasons with Oakland and Washington. He saved nine games for the Nationals last year.
Raley was recalled Wednesday but did not appear in a game for the Cubs.