He previously played cricket for Wales Minor Counties, as well as the second XIs of Glamorgan and Somerset.
During his time there, he worked with various players who would become professional cricketers, such as Jack Leach, Rory Burns, Alex Milton and Matt Hobden.
[1][3] In 2019, he was named as the bowling coach for Western Storm in the final season of the Women's Cricket Super League, which the side went on to win.
[5][6] In 2020, he was named assistant coach of Welsh Fire's women's side for the inaugural season of The Hundred.
After the tournament was postponed for a year due to the COVID-19 pandemic, head coach Matthew Mott withdrew from the side, with O'Leary stepping up into the role in his place.