An unauthorized mini bio -- as flattering as it is fluttering -- of the New York (Nassau County) Nets high-flying forward. Sport writer Bell traces the career of soft-spoken ""natural"" Julius Winfield Erring II from the days when he starred at Long Island's Roosevelt High. . .through the summers when the ""Doctor"" became a ""legend"" despite being virtually unknown outside Harlem's Rucker playgrounds. . .and up to his present superstar status. The incomparably gifted court magician directed his team to the ABA championship last season -- he led the league in scoring and was named the MVP of both the regular season and the playoffs. When the author isn't marveling at Dr. J's bag of tricks -- his myriad moves or his aerial stuff such as those soaring dunks or unique finger roll shots -- he attempts to clarify the way in which the Nets obtained Erving's services from the Virginia Squires and the Atlanta Hawks for a reported $4,000,000. Needless to say, most boosters are oblivious to the contract hassles and legal messes which enmesh their favorite athletes. Fans of all ages may be confused by one too many of those ABA-NBA-ABA moves. Back to the free throw line.