I would also throw in their psychological/mental state as well, there have been SEVERAL fighters that have not rebounded after a 1st big loss only to regain their path later in their careers, also drugs, alcohol, problems at home...those can affect a fighter trying to reach their full potential as well...look at Buster Douglas, he hit his absolute prime in 1 fight....a lot of things had to go right, and wrong, for him to get to that point