Dunn is no stranger to East Coast Conference lacrosse, spending 11 seasons at the helm of perennial powerhouse, New York Tech from 2010-2020, producing a 116-50 record, winning three ECC Championships, earning three NCAA Tournament berths, and taking home four Coach of the Year recognitions. Under his tutelage, 80 Bears were received All-Conference selection and 60 were deemed All-Americans by the United States Intercollegiate Lacrosse Association, including the Player, Attackman, and Long Pole Midfielder of the Year honors in 2014. In his time at New York Tech, Dunn also served as a part of the Athletic Department's academic mentoring program and helped to guide his team to a 3.30 GPA during his tenure, served as a member of the NCAA Division II Poll Committee, All-American Committee, and Coaches Connection Committee.

Prior to taking charge of the Bears in 2010, Dunn spent 12 seasons as an assistant coach for then-New York Institute of Technology, a time in which the program won three NCAA National Championships and appeared in seven NCAA Tournaments. The Holbrook, N.Y. native spent much of his efforts working with the Bears' defense and goaltenders, helping him to earn the IMCLA Assistant Coach of the Year award in 2007.

A former student-athlete himself, Dunn played men's lacrosse for SUNY Cortland, where he graduated with a degree in education, for four seasons, which featured three-straight SUNYAC Championshpis, three NCAA Tournament appearances, advancing to the National Championship once. He would go on to earn a Master's in physical education with a concentration in sports management from Adelphi University.

A career educator, Dunn taught physical education and coached lacrosse and football at a number of local high schools, including founding the boy's lacrosse program at Kellenberg Memorial High School, leading the Firebirds to the Catholic High School Athletic Association finals on three occasions and earning two CHSAA Coach and Man of the Year awards.