Considering people here think Wlad is actually any good, going as far as calling him great, he's probably got the worst chin of any great fighter that ever lived.
Roy Jones had a strange chin, at times it seemed very solid and he took shots well, but when you werent expecting it he dropped to the mat like a sack of potatoes. His knockouts from Tarver and Johnson were from shots that didnt look that devastating to me. Lennox Lewis is similar.
Roy Jones did not take a solid shot vs Johnson and Tarver and Mark Breland a great amatuer was not sturdy, Hearns had his weak days,Barkley and Hagler, but he traded, Carl the truth Williams, Norton once stunned ,done in.....Cotto ? sometimes looks suspect but has come back well fighting punchers not running...Lewis looked weakchinned vs Rahman and McCall but handled Briggs,Holy,Mercer,Bruno,Tyson so, yes he can fight punchers.....Vlad got caught vs Sanders, weakened vs Purity, and Drained vs Brewster but handled Peter and kept getting up vs Fast Sanders but could not be missed, seems he improved and learned how to clinch
Joe Louis and Felix Trinidad. Both hit the canvas often, but always got up to win. Well not always. The exact number of times Louis hit the canas during his career, 6 or 7 times at a guess.
Mercedes Cortes, Campas, Stephens, Carr, Lusheing, Reid, Vargas, Hopkins, Mayorga, and Jones. I needed boxrec for the first listed. Mayorga was a touch down with the glove, and Jones had him down three times. Knocked out once, against Hopkins.