Rooney began professionally boxing in 1979 and acquired a record of twenty-one wins, four losses, and one draw.
He also lost to future WBA world Junior Middleweight champion Davey Moore, who avenged an amateur loss to Rooney, by a knockout in seven rounds, on June 21, 1981.
Tyson's mobility skills in the boxing ring, especially his defensive upper-body and head movement, noticeably declined after Rooney's firing, eventually resulting in Tyson suffering his first professional loss in a fight 18 months after Rooney's departure.
Boxing analyst Larry Merchant credited Tyson's loss in the Douglas fight with the absence of Kevin Rooney in his corner.
[2] Rooney successfully sued Mike Tyson for over $4 million claiming that the latter broke a contract by firing him in 1988.