Simpkins was one of the most gifted big men of the Rick Barnes era in Friartown. He ranks in the top 25 on the all-time scoring list at PC and recorded averages of 11.8 points and 6.3 rebounds as a senior during the Friars run to the NCAA Tournament in 1993-94. His 790 career rebounds is the 10th most in Providence College history.
He was drafted 21st overall by the Chicago Bulls in the 1994 draft. The Maryland native played for the Bulls from 1994-97 and was a key reserve on Chicago's 1996 and 1997 championship teams, led by the legendary Michael Jordan. After being traded to the Warriors in 1997, the Bulls re-signed Simpkins in the spring of 1998 and he played significant minutes in the team's run to its third-consecutive championship. Simpkins' best season as a pro came in 1997-98 when he averaged 9.1 points and 6.8 rebounds per game. After seven seasons in the NBA, he retired as a member of the Atlanta Hawks in 2002.
Simpkins also played in Greece, Russia, Puerto Rico, Lithuania, Spain, Philippines, Lebanon, and Germany.