The Rangers optioned Corniell to Triple-A Round Rock on Wednesday.
Corniell was saddled with the loss Tuesday in Miami in his first appearance in the majors this season, allowing five runs on seven hits and two walks with three strikeouts over 3.1 innings. Winston Santos was recalled from Double-A Frisco to join the Texas bullpen as a replacement for Corniell, who will likely go back into the rotation at Round Rock.