Hernandez was optioned to Triple-A Gwinnett following Sunday's 4-2 loss to the Pirates.
Hernandez was called up June 17, tossing 6.2 scoreless innings while striking out nine batters over six appearances out of Atlanta's bullpen. The right-hander will now head back to Gwinnett, but he'll likely get another shot with the big-league club down the road this season.