It's fairly understandable to get KO'd by Liston or even Johansson one out of three times... but to get sparked out by Tommy Jackson twice? Floyd fought 64 times. He was only stopped by two Top Ten ATG' heavies and once by legit KO artist. I'll take Floyd in the durability department. Meanwhile he survived Bonavena, Cooper, Charley Powell, Quarry (altho on the canvas), the aforementioned Jackson and Johansson twice.
But never amounted to jack **** in the long scheme of things. Unlike two times heavyweight champion Floyd Patterson!