The Athletics optioned Hernaiz to Triple-A Las Vegas on Monday.
The Athletics had to make room on the 26-man roster after Max Muncy (hand) was reinstated from the 10-day injured list Monday, and Hernaiz was selected to move down to Triple-A. He has a .606 OPS with three steals, one home run and seven RBI over 134 plate appearances this season but has gone 3-for-26 (.115) across his last nine games. Hernaiz will work on his approach at the plate with Las Vegas and could return to the big club should the Athletics need depth in the infield.