Marquez was reassigned to minor league camp Friday, Patrick Saunders of the Denver Post reports.
This demotion was expected, as the 21-year-old hasn't played a game above High-A. That being said, he was impressive in big league camp, most recently throwing three scoreless innings in a "B" game Thursday, allowing four hits while walking a batter and striking out four. He'll head to the minors for more seasoning, but if he continues to pitch well, he could climb the organizational ladder fairly quickly.