I agree, he lay down the 2nd fight. First fight the general consensus was that he was going to kill Ali.
I would go with Joe Louis. Simply because smaller men than Ali with fast hands gave him problems. On his way to the title Ali struggled with Doug Jones, and should of been disaqualified against Cooper (not for split glove which while Angelo Dundee confirms he did it but film seem to conflict with the length of time Ali actually gained for it) for the smelling salts Ali received because no stimulant other than water is allowed under British boxing rules. Which brings me to my point of Louis. Cooper fought similiar to Louis, only with half the hand speed, half the power and half the combination punching. Plus he didn't cut like the british bleeder. Yes Louis was slow of foot, but his reflexes were quick enough to fire back when Ali attacked. It truly is a fascinating match up. Jimmy Young (who I scored a 2 round victory over Ali on my card) also comes to mind as slow but crafty with good hands. Other than Louis today's super Heavyweights just based on physical size Lewis, Wlad, Vitali may pose some problems.
Interesting,is n't it ? Someone else mentioned Oliver McCall in this thread. Another one who fought an ancient Larry Holmes. He did better than Mercer but still struggled.
Size never bothered Ali. He was just that much more quick in comparison and that much difficult to hit. Ali beats easily all of today's big men. He was just way to quick and his punches would slice his slower opposition to ribbons.
Liston second bout.... A minute or so after the fight is stopped watch Liston....the ring was filling with people and Liston is walking towards the left side of the ring and....he staggers...does a studder step. Don't think he would be faking anything at that point. Secondly his trainers said that after the bout in the dressing room Liston asked for smelling salts. It struck then odd since he never asked for these before. There were no newspaper men or officials to try to convince...just Listons handlers. Third Listons wife said she never saw any extra money from a payoff or from Liston betting against himself. Forth...the bout was investigated and no evidence of a fix was found. Fifth...read SI article written the week of the fight. Those at ringside who saw the punch felt the ko was totally legit. This includes Floyd Patterson, Cus Damato and Jose Torres. Sixth the punch was hard enough to lift Listons lead foot off from the canvas and twist his jaw to one side. My belief is that Liston was legitimately koed by a punch he never saw coming. Liston was koed by a punch he never saw.
Liston was selling it with the shudder step, dude. You are naive. Study the getting up on one knee, then the sudden "collapse" when he (Sonny) realizes JJW had screwed up the count. Sonny laid down an unintentionally hilarious acting job. Ali immediately told his corner guys to keep their mouths shut. He realized that Sonny had to be faking it. After all, he threw the punch.