The Royals optioned Selby to Triple-A Omaha on Sunday.
After being acquired from the Pirates on April 7, Selby was summoned from Triple-A on Tuesday and was able to make his Royals debut during his brief stint with the big club. He made two appearances out of the Kansas City bullpen, giving up three runs (two earned) on two hits and two walks over three innings in back-to-back appearances versus the Rangers on Friday and Saturday.