The astounding fact is that there are no players below 20 yrs in the top-100. The best is a ranking of 105 by Grigor Dimitrov, 19. I think this is something that is unprecedented. According to Todd Martin, it's because the game has subtly shifted from a game of primarily skill to a game that relies primarily on stamina and endurance. The slower courts and balls, the strings, and racquets have levelled the field skill-wise so that every body can hit the ball hard and generate tremendous spin from the back of the court. So it now comes down to a test of stamina and match-smarts. Which means the younger guys are always at a disadvantage. To me, this is a very sad state of affairs. Something has to be done or there will be no player worth looking forward to, after Fed/Nadal. Already, Murray and Djok have only flattered to deceive. Murray does not have the self-belief required to win slams, while Djok has physical limitations (lack of stamina and breathing problems). DelPo is just coming back from injury. The rest like Monfils, Cilic, Gulbis are fruitcakes and otherwise lack genuine talent.