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.