Mayfield was optioned to Triple-A Round Rock on Friday, Chandler Rome of the Houston Chronicle reports.
The announcement that Carlos Correa (ribs) and Aledmys Diaz (hamstring) would be out through the All-Star break was expected to give Mayfield some job security in the short term, but he'll instead find his way back to Triple-A. Mayfield did little offensively to convince the Astros he should stay with a .143/.163/.310 slash line through 43 plate appearances. His return to the minors suggests the Astros feel Myles Straw's ability at shortstop will suffice in a pinch.