The 22-year-old right-hander struck out four over five hitless innings as the Visalia Rawhide blanked the Inland Empire 66ers, 1-0.
Cook was erratic in his first start on April 16, walking five in 3 2/3 innings and giving up two runs on three hits. He lowered his ERA to 2.08 by limiting the 66ers to three baserunners, two of whom reached on errors.
Selected by the Diamondbacks in the 27th round of the 2008 Draft, Cook went 11-11 with a 3.66 ERA in 25 starts for Class A South Bend. He walked only 44 over 142 2/3 innings en route to earning Midwest League All-Star honors.
Former first-rounder Ethan Martin was almost as impressive for the 66ers. He allowed two hits and struck out seven over six shutout frames.