Walker started at first base and went 1-for-4 in Thursday's 3-2 loss to the Giants.
Walker returned to the starting lineup after a day off Wednesday. He was activated off the injured list Tuesday, and the Diamondbacks are easing him back to action after he missed five weeks with an oblique strain. Walker will eventually resume his role as the team's everyday first baseman. Josh Bell, who started in place of Walker on Wednesday, moved to designated hitter Thursday.