That's the problem when comparing fighters from different era's, people look at specific fights to prove their point, such as the Cooper knockdown fight, then saying a Tyson would knock him down quicker cos he was bigger and faster than Cooper, neglecting to mention that Ali fought even bigger and stronger guys than Tyson without being knocked down.

The same can be said about Lewis, people mention Mccall and Rahman as reason's why he wouldn't do well against Ali or George, but he just didn't bring his A game to those fight's for some reason or another. If we try and compare champions from different era's and speculate how they would do against each other, we should always assume that they would bring their A game to each of these hypothetical fights, as they would know beforehand their opponent will be top class.