Zac Gallen was originally acquired by the Diamondbacks at the 2019 Trade Deadline as an underrated pitching prospect in exchange for a high-ceiling infielder prospect in Jazz Chisholm. Both players have gone on to provide value to their respective new teams in the best ways they can hope for. Gallen came off a breakthrough 2019 and followed up with a Top-10 Cy Young finish in 2020. Expectations were high that Gallen would be an anchor to the starting rotation for the 2021 season.
That did not happen, as his season started with a fracture in his pitching forearm sustained while hitting in Spring Training.