The Athletics placed Severino on the 15-day injured list Saturday with a right shoulder strain.
Severino made an early exit from Friday's game due to what was originally labeled as arm soreness, but further evaluation determined the right-hander suffered a strain in his shoulder. The severity of the strain is unclear, but he'll now have to wait until at least mid-June for his next opportunity on a big-league mound. Michael Kelly will come up from Triple-A Las Vegas in a corresponding move to give the A's extra bullpen depth until they need another starter.