Ali knew how to use his advantages. Marciano wouldn't have been able to get close enough to touch Ali because he would have been kept at the end of a lightning fast jab and an occasional straight right to chase away any ideas of getting inside. Ali has superior speed and power enough to at least wobble Marciano if he felt he needed to display it. Marciano would have been reduced to lunging in, praying for a lucky shot and becoming even more of a mark for Ali.