McGuire was cast off the 40-man roster and outrighted to Triple-A Louisville on Friday.
McGuire made six big-league appearances with the Reds after joining the team in mid-September, even making a couple of starts near the end of the year. During that time, he accumulated a 2.63 ERA and 0.88 WHIP over 13.2 innings, and will continue to serve as depth for the club moving forward.