After graduating from Deep Run High School outside Richmond, Virginia, McGuire played college baseball at Georgia Tech. While at Georgia Tech, McGuire was named to the 2009 All-America First Team by Collegiate Baseball, the 2009 All-America Second Team by Baseball America, the 2008 Freshman All-America First Team by Collegiate Baseball, and was the 2009 ACC Pitcher of the Year.
On November 20, 2013, the Blue Jays added McGuire to their 40-man roster. On March 10, 2014, he was optioned to the Triple-A Buffalo Bisons. McGuire was designated for assignment on July 17, 2014, to make room for Brad Mills.
On July 24, 2014, McGuire was traded to the Oakland Athletics for cash considerations. Up to the trade, he had posted a 5.56 ERA in his first trip to Triple-A. He was optioned to the Triple-A Sacramento River Cats. When the Athletics acquired Adam Dunn on August 31, McGuire was designated for assignment and assigned outright to Sacramento. McGuire was released from the Athletics organization before the start of the 2015 season.