As I see it, some degree of saver for the HWs around 6’3”, 220 lbs is that beyond that size threshold, the rate of depreciation in P4P skill seems to notably increase. We might say of some of the SHWs that they move well “for” (relatively) a big man but in absolute terms they don’t look so hot to me. In fact, many look god damn awful. Also, IF the 6’3” , 220 lb’r sized guys can reach the SHWs and avoid the sheer application of the SHWs size advantage (via mailing, wrestling and leaning), they can certainly knock them out - the resilience of SHWs doesn’t necessarily increase in direct proportion to their greater size. Even in his own era, a smaller fighter like Frazier was subjected to the sheer physical size advantages of opponents like Foreman and Ali who stifled Joe via pushing, shoving and tying him up - which isn’t pure boxing nor too entertaining but it is what the bigger men often opt for against smaller opposition.
My suspicion is that we underrate the difficulty earlier heavyweights might have against much later fighters, if the earlier boxer were time-machined straight from their own time to the latters day, day-of-the-fight; while we perhaps also underrate the difficulty that would be faced by a boxer, coming in the time of earlier greats, having the natural physical and psychological potential of some later great, developed in ratio to the opportunity of those earlier times in ratio to how that later great had developed by the opportunities of that later day. And of course there are other match-up scenarios.
