James Surowiecki writes in the New Yorker:

Billy Beane followed a different path. Beane was frugal, Beane was shrewd. In three short years, he turned a stumbling outfit into a profitable enterprise that is the pride of its industry. If he hasn't been recognized as one of the most successful executives in America, it's only because his business isn't derivatives or microchips. It's baseball.

Beane is the general manager of the Oakland A's, one of baseball's much pitied small-market teams. The A's don't have a deep-pocketed owner or a fancy stadium, so their payroll is small--about one-third that of the Yankees. In an era of high-priced free agents, the A's should be sad-sack losers, but they've reached the playoffs in the last two years, and they've been this summer's hottest major-league team. Recently, they won twenty games in a row.

How has Beane done it? Most baseball men subscribe to familiar truisms about talent, character, and the chemistry of winning teams. Over the years, however, extensive scientific research into baseball statistics--often called "sabermetrics," after the Society for American Baseball Research--has proved most of these truisms to be false. The Copernicus of this revolution was a mechanical engineer named Earnshaw Cook, who, in the early nineteen-sixties, compiled reams of data that overturned baseball's conventional wisdom, and then presented the data to executives at a handful of struggling teams. The executives shooed him away. So Cook wrote a book, called "Percentage Baseball." Most of its assertions were irrefutable. They were also universally ignored (except by Philip Roth, who used Cook as the inspiration for Isaac Ellis, the kid genius who coaches the Ruppert Mundys, in "The Great American Novel").

Since then, thanks in large part to the work of the sabermetrician Bill James, a number of baseball executives--including Beane's mentor and predecessor, Sandy Alderson--have tinkered with the sabermetric method. But Beane is the first G.M. to build his organization around it. He and his assistants focus on things that can be measured (like someone's ability to get on base), instead of things that can't (like whether someone is a clutch hitter). Beane uses actuarial analysis to figure out, say, the odds of a high-school pitcher's becoming a major leaguer. And, in drafting and acquiring talent, he relies on sabermetric truths....