Barreto was optioned to Triple-A Nashville on Saturday.
The A's tried to give Barreto another opportunity to take over the job at second base, but he hit .106 with an 18:1 K:BB in 16 games this time around. Stephen Piscotty was reinstated from the injured list in a corresponding move, and Jurickson Profar now figures to be the full-time starter until they are ready to give Jorge Mateo a shot at the keystone.