Aguilar will serve as Oakland's designated hitter and cleanup batter in Sunday's game against the Royals.
Though he'll enter the lineup with southpaw Ryan Yarbrough on the bump for Kansas City, Aguilar appears to have settled into a pure short-side platoon role for the Athletics at this stage. The 32-year-old has been on the bench in five of Oakland's last six matchups against right-handed starting pitchers.