On July 31, 2017, the Yankees traded Mateo, along with Dustin Fowler and James Kaprielian to the Oakland Athletics, in exchange for Sonny Gray. Oakland assigned him to the Midland RockHounds and he finished the season there. In 129 total games between Tampa, Trenton and Midland, he batted .267 in 532 at bats with 12 home runs, 18 triples, 57 RBIs, and 52 stolen bases.
