Steve Chapman

March Madness is here, so for the next couple of weeks, you will not be able to turn on your TV without hearing about teams seizing momentum and players getting in the zone. We all know how unstoppable athletes can be: Once a snowball starts rolling downhill, it's hard to stop.

That may be true on a Rocky Mountain slope, but in basketball and other sports, the playing field is level. When squads or players get rolling, they don't keep rolling; they stop, and usually sooner rather than later.

Momentum is a myth. The heat of hands, even if they belong to Kobe Bryant, doesn't get much above 98.6 degrees Fahrenheit.

That's the conclusion of Tobias Moskowitz and L. Jon Wertheim in their new book, "Scorecasting: The Hidden Influences Behind How Sports Are Played and Games Are Won." The authors, respectively a finance professor at the University of Chicago Booth School of Business and a senior writer at Sports Illustrated, use advanced statistical analysis to demonstrate that much of what we staunchly believe about sports is not true.

Such as? You should almost always punt on fourth down. Offense sells tickets, but defense wins championships. Teams win at home because they play better on their own fields or are buoyed by supportive fans. None of these claims stands up to inspection.

But the most surprising discovery the authors made, Moskowitz tells me, is that the fabled phenomenon of momentum is pixie dust: It exists only in fairy tales, even if the tales are told by savvy coaches or Hall of Fame players. This finding, he tells me, is "the one nobody wants to believe."

It shouldn't be so incredible. How often do you hear that a three-point shot, a thunderous home run or a stunning interception has instantly shifted the momentum in the game? Yet if momentum shifts truly mattered, they wouldn't happen so often.

By the logic of momentum, once a team gets it, it should keep it. Rocks that fall off a cliff don't suddenly turn around and start climbing. But momentum flits back and forth like a fruit fly.

This lack of predictability is what Moskowitz and Wertheim detected when they sought evidence that streaks perpetuate themselves. A player who has sunk several consecutive baskets, it turns out, is no more likely to hit her next shot than when she's thrown up a stream of bricks. When a team goes on a scoring run, it doesn't mean it will sustain the torrent.

In fact, the authors note of NBA games, "If a team scores six or more unanswered points in the previous minute, it will on average be outscored by its opponent (by 0.31 points) over the next minute." Teams that ride winning streaks into the postseason fare no better than teams that back in.

What's the best predictor of whether Albert Pujols or Alex Rodriguez will get a hit when he comes to the plate? Not his last five at-bats or his last 25, but his average over the previous two seasons. A .220 hitter is a .220 hitter, never mind that he tore it up yesterday. A .320 hitter is a better bet, even if he's 0 for July.

Moskowitz was surprised by the absence of a hot hand effect because he played basketball in high school and says, "I felt it." But Moskowitz the economist says Moskowitz the basketball player was misled by "hindsight bias."

"I hit six shots in a row, so I feel hot," he says. "But if I'd shot them identically and they hadn't gone in, I wouldn't feel the same way."

The other mistake fans and athletes make, he tells me, is being "fooled by randomness." People take patterns as a sign that something special is going on, forgetting that mere chance can produce eye-catching repetitions that mean nothing.

If you flip a coin three times, you may get tails every time. Does that mean it's more likely to land on tails the fourth try? Or does it mean it's bound to turn up heads? Neither. The odds are always even.

So it's wise to discount those powerful, intangible forces that sportscasters are always invoking. If you're a fan, you'll see a lot of big men and big women in the NCAA tournaments. But Big Mo? Only in your dreams.

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Steve Chapman

Steve Chapman is a columnist and editorial writer for the Chicago Tribune.
 

 
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