O'Brien starred while playing college rugby as a student at Cal.
Under O'Brien's leadership St. Mary's has become one of the leading college rugby teams in the United States.
[1] O'Brien's team quickly found success, with Saint Mary's reaching the quarterfinals of the national playoffs in 2002.
O'Brien was named coach of the year by American Rugby News for the 2006–07 season.
[4] O'Brien has been recognized for his accomplishments in terms of recruiting, and developing relationships with alumni and with the school.