Lopez was optioned to Chicago's alternate training site Friday.
This is a performance-based demotion for the hard-throwing righty. Lopez has a 5.00 ERA, 1.89 WHIP and 10:6 K:BB in nine innings over three starts since coming off the injured list Aug. 22. The shoulder injury that sidelined him may still be affecting his performance, but he will nonetheless be out of the rotation going forward. Carlos Rodon (shoulder) is expected to replace him.