why do you think ugliness is a factor?
Most superstars are not ugly. In fact, almost every great player in NBA history could be considered very attractive (see Michael Jordan, Kobe Bryant, Wilt Chamberlain, etc.). There are few outliers like Bird and KD (to a lesser extent). But in general you never see superstars that are mad ugly.
Good looks is correlated with greatness in almost every walk of life.