Arizona has reassigned top prospect Tyler Skaggs to Triple-A, leaving Patrick Corbin and Randall Delgado to battle for the final spot in the rotation.

Skaggs started six games for the Diamondbacks in August and September last season, but he’s only 21 years old and has just nine Triple-A starts under his belt. Baseball America ranked Skaggs as a top-15 prospect this year and last year, but the Diamondbacks have good enough rotation depth that rushing the left-hander would make little sense.