Wide-grinning Brazilian star Ronaldinho is a force on the field and in the endorsement department. And he's only 27 years old. Denis Doyle/Getty Images
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While there is no doubting their ability, none of the three necessarily boasts the star power and crossover commercial appeal of some of the others on the list, which would suggest that their presence is a function of their enormous wages as much as it is their endorsements (though Germany's Ballack, as the biggest star in Europe's biggest economy, no doubt got a hefty lift from the folks at Adidas).

The big question is whether the numbers will continue to rise. In individual sports, odds are, they will ebb and flow with the popularity of the sport itself. A guy like Italy's Rossi, far and away the most recognizable face in MotoGP (and perhaps in the history of the sport) will continue to rake it in as long as motorcycling continues to rake in sponsorship money and media attention. It may be a niche sport, but it has a fiercely loyal following and he is hugely charismatic.

In American sports, the twin forces of salary caps (in basketball) and luxury taxes (in baseball) will somewhat curb any astronomical increase in terms of wages, which means any significant boost will have to come from endorsements. (But let's face it, agents will keep finding loopholes and ways to make salaries increase.) Whether guys like Dirk Nowitzki or Alfonso Soriano have the necessary Q rating to go to the next level with the sponsors is a question for the marketing guys. The impression is that they won't.

In soccer, too, the salaries appear ready to plateau. Even allowing for the Chelsea trio, the world's highest-paid players make only marginally more today in base salaries than they did five years ago when former Italian superstar Christian Vieri was raking it in at Inter Milan.

With Abramovich reportedly ready to close the tap (allegedly he wants Chelsea to run as a "normal business" and break even by 2014 -- fat chance!), Italian and Spanish clubs dealing with a hangover from the excesses of the last few years and a new breed of American, bottom-line oriented owner in the English Premier League (the Glazers at Manchester United, George Gillett and Tom Hicks at Liverpool, Randy Lerner at Aston Villa and possibly Stan Kroenke at Arsenal), the era of free-spending one-upsmanship seems to be coming to a close.

And, again, this would suggest that any significant spike in earnings will have to come from endorsements and other off-the-pitch sources of revenue. Looking at the soccer players on this list, you do get the sense that they're rather tapped out, whether it's because they are getting older or because they don't necessarily have the kind of global charisma necessary to sell shoes in China or sunglasses in North America.

Don't expect too many of the soccer players on this list to be here in two or three years' time (apart from Ronaldinho and, perhaps, Liverpool's Steven Gerrard). Instead, get ready to welcome Cristiano Ronaldo, Kaká and Cesc Fàbregas. Zlatan Ibrahimovic, Carlos Tévez and Wayne Rooney could make it too, but only if they develop media-friendly personalities.

That's the key. In a team sport, ability and performance alone do not determine the size of your income. It takes personality and charisma as well.