The Rangers optioned Collyer to Triple-A Round Rock on Monday, Evan Grant of The Dallas Morning News reports.
After going unscored upon in his first 11 outings in the big leagues, Collyer had allowed eight runs (seven earned) with a 7:10 K:BB over 7.1 frames covering his last seven appearances. Robby Ahlstrom is grabbing Collyer's spot on the roster and in the bullpen.