A lot of athletes who have had a history of unnatural steroid abuse also had a number of various injuries and their bodies have broken down over their careers.
Lebron does not fit the bill, yet.
Steroids, when used properly, can also prevent your body from breaking down, and can speed up recovery.
I don't think anybody's suggesting that if LeBron has used steroids / HGH that he hasn't done so very intelligently.