I have no doubt Smokin' Joe would have KO'd him with his big left hook. Ali had very long arms and Joe still managed to hit him time and again.
Will Wilder be given extra time to recover every time he gets hurt? Will Joe get more than 3 weeks notice?
Remember that left hook Molina rocked Wilder with, now imagine that's a Joe Frazier left hook! Wilder is a tentative boxer, he'll be cagey and try to counter Frazier as he comes in. Frazier will do what he does best and apply relentless pressure the kind of which Wilder has never had to face before. Wilder in fact has never had to face a real pressure fighter, Stiverne and Ortiz are both stationary counter punchers who were forced to chase the bigger man, Frazier is different, he'll bring the heat no doubt. I can't see Wilder being able to keep Joe off him. He doesn't move well enough or have a good enough jab to control distance on Frazier. His best chance is to catch him with something big as he comes in. Wilder has a punchers chance, but if he can't find that one big punch, he gets smoked by Frazier's pressure until a left hook separates him from his senses.