Selman was optioned to Triple-A Las Vegas on Saturday.
Selman has made 12 relief appearances for the Athletics this season, posting a forgettable 4.30 ERA. His 16:4 K:BB suggests things could be better for him going forward, but he won't get the chance to prove that at the big-league level for a stretch. Zach Logue was called up to take his place on the roster.