Whenever someone brings up the subject of hand speed …the first thing that pops into my head is …Sugar Ray Leonard vs Andy “ Hawk” Price
For his size, his speed and athleticism were off the charts. A puzzle who, during his peak years, no one really came close to solving.
One of the many technical mistakes RJJ was notorious for but was so damn gifted that he could simply get away with it for as long as he could. All the more reason why he was such a unique fighter despite his fundamental flaws.
Whilst in absolute terms the fastest fighter in history is likely to have operated at Flyweight or below, in terms of single punch, explosive speed from a p4p perspective, I think RJJ is the fastest I've seen.