'Coach Mack' played collegiately for Hampden-Sydney College in Virginia. A four-year defenseman for the Tigers, he played in two NCAA Division III Tournaments in 1998 and 1999. The Tiger defense also consistently ranked in the Top 10 in several defensive categories.

After college, McElroy played club lacrosse in the Washington, DC area, and volunteered as a coach at local high schools. He spent four years as an assistant coach at Northwest Catholic High School in West Hartford. He then served three seasons as an assistant at Farmington High school. In 2016, Coach Mack returned to Northwest Catholic as defensive coordinator. He has also a volunteer coach for both the boys and girls leagues in West Hartford.

Originally from Fairfield, Conn., Coach Mack was a four-year starter and senior co-captain for Fairfield High School. He won a pair of division II state championships in 1992 and 1995, as well as all-state honors as a senior.

McElroy lives in West Hartford with his wife Jen, their three daughters Elinore, Clara, and Reagan, as well as their two mutts Obie and Sammie. He owns MackLax LLC. and provides lacrosse instruction and private coaching for players age four through college.