Editor: Re: Hubert Mizell's column, "A noble fight denigrated to farce." As a former professional fighter (Tony Cancella's Stable, Tampa, 1957-60), I feel qualified to rebuff Mizell's putdown of Mike Tyson and boxing in general. Everyone knows that boxing, like politics, has always been liberally populated with shady characters. But that should not be brought up just because the fight did not have the predicted outcome. If Mizell feels boxing should be banned or somehow restricted, that's fine _ but not for the reasons he suggests: sleaze and incompetence. If every group in today's society had to meet those criteria, we would be left with nothing but the Salvation Army.