MacMath, 28, has played with three teams since being drafted fifth overall in the 2011 MLS SuperDraft by the Philadelphia Union, posting a career record of 47-54-40 with 36 clean sheets and a 1.33 goals against average. He played 103 matches over four seasons with the Union, going 34-39-29 with 28 shutouts and a 1.37 goals against average. After playing one season on loan with the Colorado Rapids, he joined Colorado full-time in 2016. There, he was the starter at the beginning of the 2016 season before the club signed Tim Howard. In his 17 starts that season, he went 9-3-5 with six shutouts and a 0.76 goals against average. In total, he went 12-12-7 in four seasons with the Rapids, notching eight shutouts and a 1.14 goals against average. Finally, he played the 2019 season with Vancouver, where he went 1-3-4 in eight starts with a 1.63 goals against average.
In addition to his MLS career, MacMath has also played on the international level with the U.S. U-17, U-20 and U-23 National Teams. After joining the USSF U-17 residency program in Bradenton, Florida, he represented the U.S. at the 2007 FIFA U-17 World Cup, playing two matches in the tournament. At the U-20 level, he helped the U.S. win the 2010 Milk Cup title and played in the CONCACAF U-20 Championships in 2011. Later, he trained with the U.S. U-23 National Team in preparation for the 2012 Olympics, playing in three matches.
Prior to coming to MLS, he was a standout at the University of Maryland, where he backstopped the Terrapins to the NCAA National Championship as a freshman in 2008. In three seasons, he went 51-10-3 with 34 shutouts and a 0.66 goals against average.