Ali never managed to nullify Frazier's left hook at all over 3 fights and he was still bloody great in everyone of their battles. He got pounded with left hooks all night in 71, held for dear life in the rematch and got battered again by lefts in Manilla. Frazier may have been a one trick pony of sorts (although I don't think he was that anyway) but in the words of Tony Bellew "it's a fvcking great trick". Foreman was the only fighter who nullified Frazier's hook and he did that by pushing Joe off with his massive strength advantage to effectively control range. No one else managed it and I'm not that sure many others could. Foreman was a uniquely gifted fighter in his way and was smart enough to see where Joe was strong ie in positioning himself to unload hooks upstairs and down and to take that asset away from Frazier. How he did it was illegal but 100% effective too.