Sonny Liston was always destined to lose that fight in 1964…Father Time was against him. A close to prime Clay was too fast & defensively tricky for a slow looking Liston.
Having said this, the single main key to victory was probably Clay’s jab… Yes, the humble jab. Clay won the battle of the jabs against a great jabber — largely because his was faster ! He consistently beat Liston to the jab & thereby took away one of the champion’s biggest weapons.
Liston could have been less aggressive— particularly w hen he realised the front foot approach wasn’t working. His pursuits were taking too long & he simply wasn’t closing the gap quickly enough…to make a long story short— not only were Clay’s hands faster but his feet were faster too… His ballet like footwork kept him well out of harm’s way.
From a defensive standpoint, Liston needed to crouch lower & keep his own hands higher. It was fairly apparent, he couldn’t slip the jab— so perhaps needed to try & block the straight punches coming his way.
But in all honesty— whatever he did, would not have been good enough against that super slick version of Ali.
Liston was beaten from both athletic & stylistic standpoints. Any modifications to his predictable approach would merely have delayed the inevitable — at that particular juncture.