Taking stock of men's players

Juan Martin del Potro is a solid, young performer with a high potential for growth. Clive Brunskill/Getty Images

What if there were a stock exchange for tennis players? The start of the 2009 season would have produced wild gyrations, week-to-week uncertainty and only a few standouts amid the sliding prospects … a lot like the real financial markets, in fact.

With the first quarter in the books, here's a look at how the players rate going into the clay season.

Rafael Nadal: BUY

Forget the Big Four; there's only one giant in men's tennis at the moment.

Nadal has managed to exceed the high expectations surrounding him this season, winning his first hard-court major at the Australian Open and following up with a title at the BNP Paribas Open in Indian Wells. It's the strongest start he's ever had, with his favorite part of the year still ahead.

There's only one nagging question: With all the energy he's expended, does he now have enough left to complete his usual sweep of the clay circuit?

On the one hand: yes, he really is that good. On the other, the 22-year-old Spaniard has also set up an unrealistic schedule for himself, committing to events at Monte Carlo, Barcelona, Rome, Madrid and, of course, the French Open. That's a grueling eight-week stretch with only two weeks of rest built in, so the likelihood of the odd loss or pullout is perhaps greater than in the past.

Overall, though, there's no one capable of regularly outperforming him on the dirt. His biggest challenge will be the bar he has set for himself in the past few years. Nadal actually feels his past successes have taken pressure off him by providing a hedge against any future letdowns.

It's a wise attitude, and should serve him well when he sets out to try to win a record five straight French Opens. That would surely establish him alongside, or above, Bjorn Borg as the greatest clay-court player in history, and send his stock soaring.

Roger Federer: SELL

It was the racket smash heard around the world, the perfect punctuation to Federer's current struggles. But by sending his frame hurtling to the ground against Novak Djokovic in the Sony Ericsson Open semifinals last week, at least Federer showed that he, too, knows something is wrong.

Having been the tour's best blue-chip performer and a model citizen over the past five years, Federer has arguably earned the right to have a lapse or even throw a racket without having to face an international inquisition.

More dangerous indicators are the nature of his losses -- he has dropped the deciding set against his three biggest rivals in the three biggest tournaments so far this year -- and his refusal to acknowledge that a pattern is now developing.

Both indicate that the current problem is mental. On the court, Federer's game has broken down at critical times in ways that suggest a little hesitation or self-doubt as he tries to grab control of a point, causing him to be a fraction late. Off the court, he appears to be taking each loss extremely hard, and the cumulative emotional toll might make it harder to bounce back.

Falling from such dizzy heights can be disorienting. Maybe it's time for the words of a fellow racket-smasher, Goran Ivanisevic: "Sometimes when you are winning too much, you think you should never lose again. I am learning to lose."

Federer will get through this learning process at some point, but things could get worse before they get better.

Novak Djokovic: HOLD

Only his run to the Miami final last week keeps Djokovic out of the SELL column. Victory over a depleted field in Dubai doesn't offset the quarterfinal defeats to Andy Roddick at the Australian Open and Indian Wells, and even Djokovic's performances last week were mixed. He tottered badly toward the end of his match against Jo-Wilfried Tsonga and failed to show up in the first set against Federer. And despite a late charge in the second set, he was thoroughly dominated by Andy Murray in the final.

His repeated problems in the heat this year are a definite concern, but if it's a simply a temperature issue and his fitness isn't at fault, the European spring weather might not bother him too much.

There'll be a lot happening around Djokovic during the next few weeks: First, Murray is looking almost certain to snatch away the Serb's No. 3 spot before the French Open. Then there are also the preparations for Djokovic's family-owned tournament in Belgrade, around which there has already been a bit of conflict.

That adds even more weight to his already-sagging shoulders, but if things go well there, it might help him going forward.

Andy Murray: BUY

His 26-2 win-loss record is the best on tour this year, and the only thing to find fault with is the timing of one of those losses. A combination of illness and Fernando Verdasco sent Murray out of the Australian Open in the fourth round. Other than that, he's been close to perfect: titles in Doha, Rotterdam and Miami, with only a pullout at Dubai and a loss to Nadal in the Indian Wells final in between.

In theory, Murray's game is well-suited to dirt, but his belief is lacking. He says his goal for the clay season is simply to "try and reach the quarterfinals of one of the big tournaments."

But despite the modest words, he's aware of the opportunity this part of the year provides. Djokovic will have to outperform Murray by over 2,000 ranking points if he wants to prevent the Scot from reaching No. 3 (which would be the highest-ever ranking held by a British player). And Murray is looking even farther ahead in his calculations. "If you got rid of the clay-court season's points, I think I would be very close to Roger, and not too far behind Rafa," he mused after winning in Miami over the weekend.

Two-time French Open finalist Alex Corretja will also be returning to the Murray team for the clay swing. There's every chance Murray could make a good run in the next few weeks and keep closing the gap with Federer and Nadal.

Juan Martin del Potro: BUY

He has started the year solidly, and a clutch three-set win in Miami against his idol Nadal has the potential to be a career-changer. He also did well to challenge Murray in their semifinal meeting the day after his marathon with Nadal, but the erratic performance was a sign that he's not yet as consistent as he needs to be to reach the top of the game.

He's now ranked a career-high No. 5, and though he's a long way behind No. 4, it's an impressive achievement for a 20-year-old. Del Potro insists hard courts are his favorite surface, but he won back-to-back clay events after Wimbledon last year and has few problems on the surface.

Last year, he was stalled by injury during this period of the season. This year looks much more promising.

Andy Roddick: HOLD

He has come up short against Federer and Nadal, but Roddick has otherwise had a solid first quarter, going 26-5 to start the year. That's the good news.

The bad news is that those numbers probably won't be moving in a positive direction for most of the second quarter.

With his wedding around the corner, it doesn't look like Roddick is putting much focus on the clay season this year. Still, anything he does on the dirt is gravy, and his stock should rise again when the grass rolls around.

Jo-Wilfried Tsonga: HOLD

Tsonga made a good if not great start to the year in winning in Johannesburg, South Africa, and Marseille, France, and producing a respectable quarterfinal result at the Australian Open. But he was extremely disappointed by France's first-round loss to the Czech Republic in Davis Cup and seems to still be searching for a little inspiration.

Injuries are always a threat and his game is not best suited to clay, which makes it hard to predict great things for the next few weeks. But if the charismatic Frenchman arrives at the French Open fully fit, the home crowd could inspire him to make a run.

Fernando Verdasco: HOLD

Injuries have held Verdasco back after his excellent run at the Australian Open, but the Spaniard should still be able to maintain his elevated form for the next few months. Hard courts have historically been better for him than clay, but it'll be interesting to see how he does at his hometown event in Madrid, where he'll be feted like a hero.

James Blake: SELL

It's been a disappointing first quarter for the 29-year-old American, with only one win over a top-30 player. Blake admits it's getting harder to recover physically from matches, and he hasn't won two in a row since early February. He did reach a quarterfinal in Rome last year, but his current inconsistency makes it hard to see a repeat of that. Even when the tour returns to grass and hard courts, it'll be a big challenge for him to get back into the top 10.

Sam Querrey: HOLD

Like Blake, Querrey produced an unexpected quarterfinal result on clay last year, reaching the final eight in Monte Carlo. Unlike Blake, however, Querrey is still on the upswing and even prefers clay to grass.

The odds are against making another shock quarterfinal, but the 21-year-old has really solidified his game over the past year and still has some upside.

Kamakshi Tandon is a freelance tennis writer for ESPN.com.