Tyson was a one of a kind HW, due to him being short for a HW, his defense, and ability to break the distance very quickly. Once Kevin Rooney was gone, he collapsed. But even at his best, Tyson didn't fight such great fighters; Holmes, Spinks, Berbick were way past their prime (Berbick was never such a great fighter anyway) and a one-handed Tony Tucker took him the whole distance. Bonecrusher Smith also went the whole 12 rounds with him and he was just good enough to carry Ali or Frazier's jock strap.