While it's very hard to say, Roy took athleticism to an entirely different level. Really, he has to be one of the most athletic guys to step into the ring, his athleticism was his game. But back to my original point, even with their physical gifts fading, if he was one of the smartest fighters of all time he would have fought past that and still won meaningful fights like guys like Leonard, Hopkins, Toney, Holyfiels all were probably smarter fighters imo.