Bruce Lee was an actor. He was in superb condition. He did the things most do....run, bag work, technique work, weights..(most fighters don't)..but there was one essential thing he did not do.....FIGHT. Not a dangerous guy. A master at self promotion more than anything. yes, the debate over that will continue to go on.
Bruce Lee is a puzzling one. Had the mind of the ultimate fighter. His understanding of the game was just transcendent. Put him in UFC, he will struggle but will find his way increasingly. Fighting was clearly very instinctive. Physically he was freakishly strong and athletic unlike I've seen - the most physically gifted fighter. So in short, he would get beat by boxers and UFC fighters today but if he dedicates himself, he'll find a way. He is the father of MMA.