Ken Norton had his issues with his chin vs anyone who was a big power puncher, other than that he was a hell of a fighter, very cagey, very strong.

Goerge Foreman had issues with opponents who could move because he couldn't land as clean on them or with as much force.

Height and reach were obstacles for Mike Tyson which he typically overcame with his upperbody movement which let's be honest was the best next to Ali and Vitali Klitschko in terms of being a heavyweight avoiding punches to the head....his lack of dedication to training at the end of his prime really made it hard for him to continue being as dominant of a fighter as he could have been.