Hired as the 3d Colorado Boys Manager, Mike had an immediate impact on the lacrosse community in Colorado. He served as the defensive coordinator at Mountain Vista High School for several years and coached for BOCO Lacrosse (club) in Boulder prior to 3d Lacrosse as well as playing a season with the Rochester Rattlers MLL team in 2015. Mike began coaching girls lacrosse in 2016 and in 2018 assumed the Girls Senior Manager position for 3d Colorado.
In the summer of 2018, O'Neil played as a defensive midfielder for the MLL Dallas Rattlers seeing significant playing time en route to the Rattlers best overall season in recent years.
Mike attended Cornell University, starting for the Big Red in all 54 games as a midfielder and earning Rookie of the Year honors in 2011. He also won three Ivy League Titles during his four years, including a quarter final appearance in 2011 and a Final Four appearance in 2013. Mike earned a Bachelor of Science degree in Environmental Science and Business in 2014.
Mike began playing lacrosse at Fayetteville Manlius High School in upstate New York and earned All-American Honors during his senior year. He obtained his strong passion for the game and coaching while growing up under the tutelage of his grandfather, Tom Hall and uncle Geoff Hall. Tom Hall started the Fayetteville Manlius Lacrosse program, and Geoff continues to coach at Fayetteville Manlius.