There's Joe Louis , Alexis Arguello , and Julian Jackson. 3 fighters that should be in any text book on how to get maximum leverage through perfect technique on any punch. Theirs a few fighters that may have hit harder with a particular punch like Hearns's straight right hand or Fosters left hook. But few had the ability to ko WORLD CLASS opponents as cleanly as those 3 could. Jackson's technique, leverage, timing ,speed and power were all top tier. it was so devastating he rarely needed to demonstrate if he had a great ability to finish hurt opponents. unlike a fighter like Ray Leonard who didn't have Jackson's firepower, but was deadly and would rarely allow a hurt opponent off the hook. Jackson rarely had to set up a ko, they seemed to just happen.