Estes was optioned to Triple-A Las Vegas on Sunday.
The right-hander made a spot start Saturday against the Rockies and will return to the minors after giving up four runs over 4.1 frames in a no-decision. It was the first MLB outing of the campaign for Estes, who has a 5.95 ERA, 1.49 WHIP and 39:28 K:BB across 59 innings (12 starts) at Triple-A this year.