The Mariners optioned Castillo to Triple-A Tacoma on Thursday.

EDGE Analysis

Castillo's time with the big-league club was less than spectacular, as he'll head back to the minors after giving up seven runs (six earned) over seven total innings alongside a 5:7 K:BB. With George Kirby (shoulder) not expected back until May, the Mariners are again left with an opening in their rotation, and it's currently unclear who will be chosen next to fill the gap.