The right-hander was moved to the bullpen Saturday, giving him a chance to try to fix problems in his delivery. He retired only two batters in his last start, an 11-2 loss in San Francisco on Monday.
Volquez returned in July, less than a year after he had reconstructive elbow surgery. He's throwing hard but has been wildly inconsistent.
Volquez was scheduled to start the final game of a series against the Chicago Cubs on Sunday. Instead, rookie Travis Wood will take his place. Reds manager Dusty Baker says Volquez will work on his delivery in the bullpen and be available in relief.