A remarkable if slightly obscure statistic that has emerged from Novak Djokovic's clinching the year-end No. 1 ranking for 2012—courtesy of a fantastic season no doubt, but more immediately of Roger Federer's withdrawal from Paris—is that this marks the first time in five years anyone has defended their year-end standing atop the rankings.
The last man to do so was Federer himself, who in the course of a 237 consecutive week reign as No. 1 ended 2004, 2005, 2006 and 2007 with that ranking. Rafael Nadal was the first player to succeed him to the post in 2008 but was unable to maintain it in 2009 by virtue of injury, and Federer regained it in 2009 to become the first person to do so since Ivan Lendl in 1989.
Nadal made it a bit of a see-saw in 2010 when he wrest it from Federer again, while in 2011 Novak Djokovic fulfilled a childhood dream in becoming the first person since 2003 other than Federer or Nadal to end the year ranked No. 1.
The fact that he has managed to do so again in 2012 might initially incite suspicions that a new sense of continuity, embodied in Djokovic, is beginning to emerge.
In some important respects, however, this new reign of Djokovic cannot be compared to Federer's in 2004-05, when he first defended the year-end No. 1 ranking. Certainly the top ranking rewards consistency at the highest level, of the highest order. Djokovic has played with such consistency—reaching the semifinals in all played so far but one (Madrid Masters), and reaching three Grand Slam finals, winning one (Australian Open).
Still, he has only managed five titles this year—the Australian Open, Miami, Toronto, Beijing and Shanghai, a full half of his title haul last year. If anything, this reflects both the stellar nature of his 2011, but also the toughness of his competitions—he has essentially topped the rankings for two years, but a few mishaps or wrong shots at wrong moments have made the difference between titlist and finalist. The three finals he lost to Nadal at Monte Carlo, Rome and Paris, for instance, bear this out strongly.
By contrast, Federer's 2004 and 2005 campaigns were utterly dominant, in both years accruing 22 titles, and seven majors overall. Djokovic—15 and four respectively. He had a 24-final winning streak over that time, defending both his Wimbledon and US Open crowns.
If anything, 2005 was better than 2004 for Federer, despite having only won two majors instead of the three in 2004—he reached the semifinals of all four slams, losing in the first two in tight contests that, had he won, would have placed him very nicely for the calendar Grand Slam.
But for the Australian Open, 2005 was almost a copy of 2004, defending almost all his titles. It was a year that, if anything, consolidated his domination over tennis.
Quite the same, it is very difficult to say with Djokovic. He certainly hasn't been able to defend half his victories from 2011, although the very fact that he has been so consistent over a two-year period, in the era of competition that exists now—without entering the controversial topic of the relative competitiveness of eras, it is at least clear that if someone has played both Federer and Nadal, heavy candidates for the GOAT title and been able to best them over a calendar season, that someone must be darn good—speaks volumes about the quality of Djokovic's tennis, and the new face of domination in tennis.
Perhaps men's tennis is entering an era now when monopolies and duopolies a la Federer-Nadal may no longer be possible. Certainly Djokovic-Murray in recent months has attained almost a grandeur, but it is clear that terms like the Big Four are bandied about quite regularly for good reason.
The best Djokovic has done is the best anyone would have been able to do in this 2012 season, when four players have won the four majors. He has had the best season anyone has had, titles notwithstanding, and if that is the best to be seen it is the kind of domination that will probably be possible from now.