The Yankees optioned Warren to Triple-A Scranton/Wilkes-Barre on Saturday.
Warren gave up four earned runs over four innings during his spot start Saturday, and the Yankees will waste no time sending him back to the minors. The 25-year-old righty now owns a 9.55 ERA and 1.85 WHIP through 21.2 innings across five MLB starts, and his demotion to Triple-A opens up a slot in New York's rotation for Luis Gil (back) or Clarke Schmidt (lat) to fill once one of them returns from the injured list.