The A's also announced Monday that they have claimed outfielder Kenny Wilson off waivers from Toronto and optioned him to Triple-A Sacramento. In addition, Oakland outrighted outfielder Nick Buss to Sacramento and traded International Slot No. 57, worth $339,000, to Milwaukee for minor league pitcher Rodolfo Fernandez.
Mills went 1-1 with a 4.41 ERA in three starts for Oakland this season. But with Hammel scheduled to pitch Wednesday at San Francisco, the A's needed to clear space on the roster.