Even if Steven D. Levitt's blurb wasn't on the cover, you'd quickly get the idea that "Scorecasting" is the sports equivalent of "Freakonomics." Subtitled "The Hidden Influences Behind How Sports Are Played and Games Are Won," the most important and fascinating sports book in years has been written by an odd couple: Tobias J. Moskowitz is a professor of finance at the University of Chicago, while L. Jon Wertheim, a distinguished tennis writer, is a professor at Princeton.

They are not the kind of guys who listen to your assertion and tell you that you are wrong; they are the kind who will take nearly any standard sports assumption (i.e., that offense wins championships) or question (such as "Why does the home team have an advantage?"), analyze the data, and come up with an eye-popping but ultimately plausible conclusion.

In "The Myth of the Hot Hand," for instance, they conclude, "In every single sport (MLB, NBA, NHL, NFL, European soccer) we studied, we found ... the true quality of teams can be measured best in large samples." Which means that a team's overall performance over the regular season is a better predictor of postseason or tournament success than its most recent games.

Moskowitz and Wertheim aren't out to tell us that everything we know about sports is wrong -- it's more that even when we're right, it's often for the wrong reasons. In the chapter "Comforts at Home," they confirm what any sports fan has known for years about the advantage of playing on your own turf, that "The size of the [home field] advantage is remarkably stable in each sport. ... The home team's success rate is almost exactly the same in the last decade as it was 50 or even 100 years ago." And it's that way in every sport, from baseball to soccer and even to international cricket.

But why? After careful examination and elimination of most common assumptions, such as the rigors of travel and the noise of the home crowd, Moskowitz and Wertheim arrive at the surprising conclusion that in nearly every sport, the difference is ... officiating, which is almost always skewed slightly toward the home team. The explanation: "Home teams receive fewer penalties per game than away teams -- about half a penalty less per game -- and are charged with fewer yards per penalty."

In baseball, "Home teams are more likely to be successful when stealing a base and when turning a double play, yet the distance between the bases is identical in every stadium." Or, as they put it, "What we found is that officials are biased, confirming years of fans' conspiracy theories, but they're biased not against louts screaming unprintable epithets at them, they're biased for them."

"Scorecasting" will change the way you watch sports, but be careful when you start reading it -- you're liable to get lost in it and miss the game.

Allen Barra's latest book is "Rickwood Field: A Century in America's Oldest Ballpark."