Hamilton was born in Toronto and grew up in Peterborough, Ontario. He played hockey as a freshman at Princeton University, then became a pitcher for the baseball team. Hamilton was on the Ivy League champions in 1991. He also was assistant coach two years at Princeton. In 1992, Hamilton was hired as pitching coach for the Team Canada. He got a job as pitching coach and GM of the Barracudas de Montpellier of Division Élite in France in 1993 and helped the team to three titles in a row, their most successful run to date (as of 2007). Part of his success came from his recruitment of Jeff Zimmerman, who became the most notable player to emerge from the French league in the 20th Century. He was pitching coach for the French national team in 1994, making him pitching coach for two senior national teams on different continents.
Hamilton left Team Canada in 1996 to become head coach of the Canadian junior national team, leading them to a Bronze Medal in the 1997 World Junior Championship. He was named Baseball Canada Coach of the Year that season. It was also his last year as Montpellier's coach and GM.