60's Ali vs Frazier, Foreman, Norton and Holmes

Ali of 63 and Ali of 65-67 are different fighters. I presume you're referring to the Cooper knock down which was as much about Ali just clowning around waiting for his prediction to come true than any susceptibility to a left hook. But besides that I never saw Ali showing left hook susceptibility post Liston.

 

Ali moved like a Welterweight in the 60s. Big difference between his dancing then and his " dancing" in the 70s. Plus it's not like he just moved and did nothing, as foreman would close in he'd pepper him with punches and slip and slid and move again.

Make no mistake had 70s Ali fought Sonny Liston he may have had to employ rope a dope too.