Deasy was born in August 1960 and first played Gaelic football in Sacred Heart BNS in Ballygall and then in St Kevin's Secondary School. His class and school team-mates included Dublin stars Barney Rock, Gerry Hargan, John Kearns and Anto McCaul. These players formed the backbone of Ballymun Kickhams SF team who first won the SF championship under Deasy's captaincy in 1982.[citation needed]
Deasy first played for Dublin under Kevin Heffernan in 1982 and played on and off under successive managers up to 1996. Deasy must be unique in that he has played for Dublin in all the centre spots from full-forward, centre-forward, mid-field, centre-half before finding his niche at full back from 1993 to 1996. He gained a regular spot at full-back at almost 33, an age most players retire. Ironically, he replaced the younger Gerry Hargan on Hargan's retirement.[citation needed]
During his three and a bit years at the top of Gaelic football, Deasy won four Leinster medals, one All Ireland Medal, received three All Star nominations, winning one. He also won one National Football League medal, also receiving the Man of the Match Award for keeping Tony Boyle, then Ireland's top forward, scoreless in the final and the replay.[citation needed]
Deasy remains heavily involved in the GAA and now referees at club level.[citation needed]
