Baseball aficionados might conclude that all of this points to some pernicious new trend in the market for top players. But this is not specific to baseball, or even to sport. Consider the market for pop music. In 1982, the top 1 percent of pop stars, in terms of pay, raked in 26 percent of concert ticket revenue. In 2003, that top percentage of stars — names like Justin Timberlake, Christina Aguilera or 50 Cent — was taking 56 percent of the concert pie.

The phenomenon is not even specific to the United States. Pelé, from Brazil, the greatest soccer player of all time, made his World Cup debut in Sweden in 1958, when he was only 17. He became an instant star, coveted by every team on the planet. By 1960, his team, Santos, reportedly paid him $150,000 a year — about $1.1 million in today’s money. But these days, that would amount to middling pay. The top-paid player of the 2009-10 season, the Portuguese forward Cristiano Ronaldo, made $17 million playing for the Spanish team Real Madrid.

Of course, the inflated rewards of performers at the very top have to do with specific changes in the underlying economics of entertainment. People have more disposable income to spend on entertainment. Corporate sponsorships, virtually non-existent in the age of Pelé, account today for a large share of performers’ income. In 2009, the highest-earning soccer player was the English midfielder David Beckham, who made $33 million from endorsements on top of a $7 million salary from the Los Angeles Galaxy and AC Milan.

But broader forces are also at play. Nearly 30 years ago, Sherwin Rosen, an economist from the University of Chicago, proposed an elegant theory to explain the general pattern. In an article entitled “The Economics of Superstars,” he argued that technological changes would allow the best performers in a given field to serve a bigger market and thus reap a greater share of its revenue. But this would also reduce the spoils available to the less gifted in the business.

Image In sports as in business, pay has soared at the very top of the scale. Last season, the soccer superstar Cristiano Ronaldo, right, made about 15 times as much as Pelé did in 1960, adjusted for inflation. Credit... Left, Agence France-Presse; right, Pierre-Philippe Marcou/Agence France-Presse — Getty Images

The reasoning fits smoothly into the income dynamics of the music industry, which has been shaken by many technological disruptions since the 1980s. First, MTV put music on television. Then Napster took it to the Internet. Apple allowed fans to buy single songs and take them with them. Each of these breakthroughs allowed the very top acts to reach a larger fan base, and thus command a larger audience and a bigger share of concert revenue.