Coach Donnellan grew up in Marin County and played basketball at Marin Catholic High School before going on to play at the University of California, at Davis. In 1981, Coach Donnellan was selected as a first team all-league player while leading the Marin County Athletic League in scoring, averaging 20.6 points per game.
Coach Donnellan began his coaching career in 1989 as the Junior Varsity Boys’ Head Coach and Varsity Boys’ Assistant at Sir Francis Drake High School. From 1989-1991, he captured three straight MCAL titles with his JV teams while assisting legendary Drake coach Pete Hayward at the varsity level. In 1992, Coach Donnellan became the Varsity Boys’ Head Coach at Drake and coached the team for 23 seasons, amassing 445 wins. His varsity teams won ten Marin County Athletic League titles, two North Coast Section crowns, and two Northern California championships. Eighteen of his teams participated in the North Coast Section playoffs, with seven of those squads advancing to the Northern California regional state playoffs. His 1994 and 2014 teams captured the Northern California championship and appeared in the California State Championship game.
Over the course of his career at Drake, Coach Donnellan helped develop 16 players who went on to have successful careers at the collegiate level, including five who played at the Division 1 level and six who played professionally in numerous countries.
Coach Donnellan ranks 3rd on the all-time list for Marin County Athletic League wins with a record of 215-105 (67.2%) and is the winningest coach in Drake history. In November of 2010, Coach Donnellan was inducted into the Marin Athletic Foundation’s Hall of Fame. The North Coast Section named Coach Donnellan their 2013 Basketball Honor Coach for his contributions on and off the court. In 2014, he was named the Northern California Division 3 Coach of the Year.
Coach Donnellan has been coaching the 17U Showcase team for the North Bay Basketball Academy since 2013, and is the NBBA Director of Camps and Director of Coaching.