Michael O'Leary represented South Australia in the 1990 under 17 Teal Cup carnival held in Brisbane. In the same year he played four games for the Norwood under 17s, two for the under 19s and another two for the reserves.
In 1991 and 1992 he continued his development in the under 19s and reserves.
O'Leary made his senior debut in the 1993 pre-season Foundation Cup series. He played three league games in his first year, and another three in 1994. Strongly built, he was possibly best suited to a half forward flank.
O'Leary later joined Sturt and played 18 games (1996-1997).
He has coached several clubs in the South Australian Amateur Football League, with stints at Old Ignatians, Adelaide University, St Peter's Old Collegians and Pembroke Old Scholars.
R Cialini Nov 2021