Wimbledon Tennis Tour pics

The answer is relatively simple: Nadal capitalized to the utmost on two critical lapses by his rival one at Wimbledon, where Federer was upset by Tomas Berdych, and one at the U.S. Open, where he was taken out by Novak Djokovic. That Nadal was able to take advantage of those opportunities tells us a great deal about where the ATP Tour is today, but it also makes an oblique comment on the state of the WTA game.

On the ATP side, the evidence suggests that we're living the absolute best years tennis has ever known. It has a rivalry that resonates far beyond the stadia where tennis is played, and the consciousness of the niche tennis audience. The entire world knows, and seems to care, about Rafa versus Roger.

At the same time, the titans have not exercised utter dominion over the men's game, which is always the danger in rivalry. (Surely you remember sitting around, twiddling your thumbs, waiting for the predestined Chris versus Martina final.) Novak Djokovic, Tomas Berdych and Robin Soderling inserted themselves into the main narrative of 2010, in an explosive way, at critical moments that left us hoping rather than merely waiting for another Grand Slam final between Roger and Rafa.

Let's also remember that exactly one year ago, a third name was in the mix at the very top, that of 2009 U.S. Open champion Juan Martin del Potro. I don't even want to think how competitive the men's game would have been had del Potro not suffered a wrist injury that kept him out of action for almost this entire year.

The men's game in 2010 had depth at the top and depth at every other level. I can't imagine men's tennis being in a healthier state than it is at the moment.

It's a little different on the women's side, where the lack of depth at the top is an outstanding shortcoming. It's fitting that the year-end No. 1 ranking went to Caroline Wozniacki, who did not win a single major, because when you don't have a dominant champion or two, the honors go to the last woman standing. And though the WTA has a good number of Grand Slam champions, it doesn't have a dominant one.

The year just ending was undoubtedly the Year of Rafa, as the Spanish lad, already an international icon, completed his career Grand Slam. But in one sense, 2010 ought to be given a one-month extension because this is an ongoing story. Should Nadal win the upcoming Australian Open, he'll be the first man since Rod Laver in 1969 to hold all four majors. Can you say, "Serena/Rafa Slam?"

One of the more interesting aspects of Rafael Nadal's feat is that he accomplished it in the era dominated by the consensus GOAT (Greatest of All Time), Roger Federer, leading us to wonder, "Gee, how did he do that?"

This is unfortunate because the WTA now has something it has historically lacked: solid depth through the top 15 -- and beyond. When players of the caliber and potential of Victoria Azarenka (No. 10) and Jelena Jankovic (No. 8) are more or less second-tier floaters, the game is in good shape -- better shape than the controversy of a Slam-less No. 1 suggests.

Then there's this: the two stars who returned to the game in 2010, Kim Clijsters (granted, she came back after the midpoint of 2009, but this was her first full year since a lengthy "retirement") and Justine Henin. They didn't waltz back in and dominate, as some predicted they would. Clijsters ended the year at No. 3, just ahead of the Williams sisters, Serena and Venus. Henin pulled her stakes after suffering an elbow injury at Wimbledon, and we have no real idea of her future plans.

It's a good thing for the WTA that whatever she decides doesn't appear to be a pressing co