According to the Random Walk theory, what will happen in 2010 is best predicted by what transpired in 2009.
If only we should be so lucky.
Last year was as dramatic as any, seeing Roger Federer fall and rise, Robin Soderling becoming a known entity, and Juan Martin del Potro climbing to the ranks of the elite.
As for 2010? No one knows, but here are some things to keep in mind.
2009 was a very good year for the man they call Jo-Willy.
The Australian Open has a habit of producing flashes in the pan (see Schüttler, Rainer and Clément, Arnaud), but the 2008 finalist cemented his status as a legitimate top 10 player with solid performances in the Majors, along with wins in Tokyo, Marseille, and Johannesburg.
Tsonga is the joker of the pack, possessing a game that can pretty much beat anyone on its day, but his fortunes in 2010 will depend on the timing and proportions of his two I's: injury and inspiration.
Verdasco, like Tsonga, had respectable performances at the Slams, where he didn't lose to anyone he shouldn't have lost to. And, of course, who can forget his epic Australian Open semifinal against Rafael Nadal?
Always a very capable shotmaker, the penny dropped in his game last year when he discovered the benefits of Gil Reyes Jr., the former conditioning coach of one Andre Agassi.
His work in the offseason may prove to be most pivotal; the heat in Melbourne places a premium on fitness, and no one will have the benefit of a lot of matches under their belt.
A good result could provide the momentum for a climb up the rankings.
After Roger Bannister broke the four-minute mile, a host of other runners followed close behind. Bannister may not have been the fastest man of his era, but he was the first, and he showed them all it could be done.
Enter Robin Soderling.
Just when there seemed to be no stopping Rafael Nadal, in came Soderling, pushing him around in a manner somewhat reminiscent of Tsonga circa Australia 2008—only nobody pushes Rafa around on clay.
Once the tennis equivalent of watching paint dry, Soderling discovered the benefits of combining aggression with a 6’4” frame.
But like anyone who is good but not great, his place is not assured. Watch him play and you can see why he is in the top 10, but you can also see that it wouldn't take much to knock him out of it.
After his epic and heartbreaking Wimbledon loss, Roddick remarked that Roger Federer isn't given enough credit for his toughness; the same could be said for Roddick.
With the world at his feet at the end of 2003, along came Federer, and then Nadal, and then Djokovic, and Murray, and del Potro.
Compared to those ahead of him, he’s not the most talented. But that serve opens a lot of doors, and with a couple breaks, he could see his way to an Open victory this year.
No one would deserve a major title more, as Roddick has done yeoman's work in rounding out his game and simply refusing to give up.
Davydenko is seemingly the man about whose game people have the least to say.
His win at the ATP Finals portends good things to come in the new year. Davydenko has a style suited to Australia; he's fit and fast, very consistent, and can construct a point. But look for him to do the most damage at the Masters Series events.
Appearance-wise, no one in recent memory is as physically imposing as Rafael Nadal. Yet del Potro, who in his sleeveless tops looks malnourished in comparison, is the one player who can physically impose his game on his opponent like no other.
His height makes him immune to topspin, and his impressive movement allows him to cover the court and dig out the low shots. Perhaps no one in the game hits the ball harder.
It will be interesting to see how his game adapts to carrying around extra weight as his body inevitably fills out, but that is many years off.
He has game, and after getting that first kiss out of the way at the US Open, 2010 may see del Potro climb near or to the top.
With a first-class tennis brain and perhaps the best wheels in the game, Murray is capable of bending the wills of men—but that should be in no way confused with imposing a will of his own.
And without any other big weapons to speak of, therein lies the problem with Andy Murray.
Another problem is Wimbledon. His form was the model of consistency last year, and it is that consistency that positions him well, should a break go his way at the Majors.
But it is his consistency that could fall victim, should his world center around just one tournament.
In 2009 Djokovic visibly took a step back; there was no major title, and his confidence dipped after he gave Nadal all he could handle at Monte Carlo and Rome but still came up short.
But he quietly took two steps forward.
He ended the year playing some excellent tennis, and has been working hard on the net game—a game of percentages well suited to someone whose shot selection displays a profound understanding of risk and reward.
Like everyone else, his fortunes have been dependent on what the top two are doing. But unlike them, Nole finds himself on the fun side of the aging curve.
This year should see him play a larger role in determining his own fate.
On the morning of May 31st, 2009, Rafael Nadal fans had to use welder's glass as they gazed into the future.
A fourth French Open title seemed a certainty, defending his Wimbledon championship seemed likely, and, given his Australian Open title that transformed Roger Federer into a water fountain, a calendar Grand Slam seemed a distinct possibility.
What we didn't know was that he was already injured, but what we now know is what happened next. 2009 saw Nadal's most significant physical breakdown to date; even after returning to play, he was never really the same.
It will be interesting to see if Nadal is fully recovered in 2010; of even more interest is how he fares, now that his matchup problems have been exposed by Soderling and especially del Potro.
They have no problem handling high balls to their backhand, and furthermore their hard flat strokes rob Nadal of time, which is key to him setting up his shots.
Still though, the list of tall players with tons of game and two-handed backhands doesn’t run long.
But surely Djokovic has taken note, and Tomáš Berdych or Marin Cilic waking up on the right side of the bed may now be the Mallorcan’s early round bogeyman.
But Rafa should rest easy: when healthy, he’s got as much game as anyone.
After the 2008 Wimbledon Final, many people thought Roger Federer was done. Fast forward a year, and everyone was calling him the greatest.
The difference between those two years? A handful of points in an epic five-set final.
Imagine if, in 2010, he were to win the first three majors, but lose the US Open to del Potro in a marathon fifth-set tiebreak.
There would be those who would question his mental toughness for losing a tight one, and say that he’s no longer the best—much less the greatest—because he isn't even better than del Potro.
An exaggeration for sure, but at times we’re guilty of judging Federer’s performances against the ghosts of perfection.
Part of it goes back to what Roddick said: Federer makes it look too easy; if he had an awkward-looking forehand, he’d suddenly look like an overachiever. Another part of it is the knowledge that it could be a very long time before these heights are approached again.
In 2010, two things are present that weren’t there before: the first is his family. The second is the fact that everything he does now is just gravy where his legacy is concerned.
How these things affect his motivation is the big question, but determining what goes on inside a man’s head is trickier than predicting the future.
Still, he’s gone on record and said he wants to just keep on playing. For the past 24 major tournaments, he’s either won or lost to the eventual champion, never exiting before the semis. That takes a lot of heart and dedication, no matter the talent level.
For the year to come, is there any reason to expect that there won’t be more of the same?