Barreto was optioned to Triple-A Nashville on Friday.
Barreto is still the best of Oakland's prospects, but he wasn't able to do enough to convince the Athletics to forego an extra year of control and bring him up with the big club. The Athletics will stick with Marcus Semien and Jed Lowrie up the middle for now, but expect Barreto to be the man at one of those two positions for the A's in the very near future.