Simpson will undergo surgery Tuesday to repair the ulnar nerve in his left elbow, Christina De Nicola of MLB.com reports.

EDGE Analysis

It's expected to be around three months before Simpson will be ready to pitch in games again, so this will put him out at least until after the All-Star break. The southpaw initially suffered the injury during spring training and made an unsuccessful attempt at resting and rehabbing the injury before eventually opting for surgery.