I once read a book by Rod Laver in which he plain out said the Billie Jean King vs. Bobby Riggs was purposely thrown by Riggs. If you think about it, it does not make sense that Billie Jean would challenge Bobby after he demolished Margaret Court who was ranked higher than King at the time.
Some who should be on the list are Jim Thorpe, Bart Starr, Joe Louis, Rocky Marciano, Ty Cobb who was not the person portrayed in the movie, Bear Bryant, I might put Michael Jordan on the list simply because of his athletic ability, Don Hutson, and Roger Staubach.