Oakland reinstated Hernaiz (ankle) from the 60-day injured list Friday.
Hernaiz had been on the injured list since May 8 due to a left ankle sprain. He started his rehab assignment at Triple-A Las Vegas on July 20, and across his nine games, he slashed .364/.432/.545 with two stolen bases, three doubles, one home run and two RBI across 37 plate appearances. To make room for Hernaiz on the 40-man roster, the Athletics transferred right-hander Luis Medina (elbow) to the 60-day injured list. Hernaiz had been given a brief look in an everyday role prior to landing on the IL, but he may have to settle for a utility role upon his return with Zack Gelof, Abraham Toro and Max Schuemann seemingly locked in as Oakland's starters at second base, third base and shortstop, respectively.