John:
Like I said in a previous post, people see things through their own prisms.
You forget to point out that they also went to the ground. It's hard to see on the youtube video, but, Ali flops to open guard, where Frazier briefly stands over him until he's pulled off. I've trained with all types of boxers, and I've never seen this move done. EVER.
BTW: I think I saw a bear use a similar clinch/tactic when it fought a wolverine on National Geographic. Bears are famous for their boxing.
The point that people tend to miss when these examples are brought into a discussion is that the very nature of unbridled, unsanctioned combat often leads to a breakdown of the conditioned response, simply because of how the nervous system is built. It's beyond discussion of style and training method, but rather about how our nervous system has these hard-wired programs in our bodies.
A conditioned response (20 years of boxing, judo, bjj, etc.) tends to give way to the instinctive response (sprinting, swinging, flinching, covering up, grabbing, pushing, pulling, etc.) because of how hard-wired these responses are to the fight/flight/freeze response. In other words, you can train a jab or a high-single from now until doomsday, but if a stimulus causes adrenaline dump, catalyzing the fight/flight/freeze response, the body will revert to these hard-wired responses. This is the nature of the nervous system, and this is how our species has survived over several million years.
And this is why there are so many examples of boxers not using the jab/cross/uppercut/hook/shoeshine/philly shell...when the perennial $hit hits the fan: genetically hard-wired responses overtake them in a fight/flight situation.
This is why, in the long-run, these long-winded discussions about style add up to nothing, because a biochemical response in our bodies will override all that training. Boxing, wing chun, TKD, hung gar...all reduced to grabbing, falling, shoving. Combat, as one man pointed out, is simpler (biochemically at that) than most people would like it to be.