Parker, 27, had been on the DL since June 6 with a right elbow stress reaction. He was called up from Triple-A Iowa on May 17 to make his Major League debut, and did not give up an earned run over 4 1/3 innings in four outings.
He made eight rehab appearances with Triple-A Iowa and gave up six earned runs over 10 2/3 innings, striking out 13 and walking one.
Hinshaw was claimed off waivers from the Padres on Aug. 19, and gave up five runs over one-third of an inning in two appearances. On Monday, he gave up five runs on four hits and failed to retire any of the five batters he faced.
Cubs manager Dale Sveum said the bullpen was in pretty good shape on Tuesday despite needing outfielder Joe Mather in the ninth inning on Monday. Mather faced two batters and threw four pitches. He gave up a single to pinch-hitter Jeff Bianchi and got pinch-hitter Martin Maldonado to end the inning with a groundout. Milwaukee scored nine runs in the frame.