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Playing the Numbers
January/February 2011
Reviewed by Ian Ayres '81, '86JD
Ian Ayres ’81,
’86JD, is the William K. Townsend Professor of Law at Yale Law School and the
author, most recently, of Carrots and
Sticks: Unlock the Power of Incentives to Get Things Done.
Scorecasting: The Hidden Influences Behind How Sports Are Played and Games Are Won
Tobias Moskowitz and L. Jon Wertheim ’93
Crown
Archetype, $26
Thank you, Camp
Young Judaea, for assigning two sports-crazed 12-year-olds to bunk seven in
1984. These two onetime bunkmates, despite divergent career paths, have
remained lifelong friends—and have now written a book on behavioral economics
in sports that I had trouble putting down. Tobias Moskowitz is a finance
professor at the University of Chicago, while L. Jon Wertheim ’93 is a senior
writer for Sports Illustrated. Following in the same journalist-scholar coauthorship model of the phenomenally
successful Freakonomics franchise, Moskowitz and Wertheim have found a way to convey fascinating social
science results through easily accessible storytelling. Scorecasting is not a very compelling or descriptive title, but if you are looking to buy a
present for a sports fan, you can’t go wrong with this book. Indeed, its
super-short chapters are the perfect length to fill the commercial breaks while
watching your favorite team.
The book is
chock-full of surprising findings across all of the major professional sports
organizations. You’ll learn that the Chicago Cubs never win the World Series in
part because their fans are so long-suffering. You see, the demand
for tickets at Wrigley Field is relatively insensitive to the team’s win/loss
percentage, so management has less reason to invest in making the team a
contender. If there were more fair-weather fans, there might be more fair
weather.
But what makes
the findings in Scorecasting so memorable is how the authors tie common sports phenomena to a few recurring
cognitive biases. One of book’s central investigations is an attempt to explain
the marked home court advantage that can be seen across a wide variety of
sports. Moskowitz and Wertheim systematically examine a variety of traditional
and not-so-traditional hypotheses. For example, they reject the possibility
that athletes actually perform better at home by looking at isolated behavior.
Turns out the percentages of successful free throws and field goals are the
same when athletes are playing at home as when playing away.
Instead, the
authors find support for the idea that referees favor the home team because of
what psychologists call “social influence.” According to this theory, referees are subtly influenced by being in a stadium with
thousands of people who want a particular result—and call the games
accordingly.
I was initially
skeptical, but the book shows that the degree of the referee bias is itself a
function of the size of the crowd. When there are fewer people in the stands,
the data show, there is less of a home field advantage. The trend is easiest to
track in baseball, where an “electronic eye” shows the size of the effective
strike zone for the home and away teams—and how much they can differ. There are
exceptions: in the NBA, schedulers are actually responsible for about a fifth
of the home court bias; “visiting teams play the vast majority of back-to-back
games,” so the away team is more likely to be tuckered out. Professional
leagues could lean against the home field advantage, but they have good reason
not to—because ticketholders will pay more to see their team win at home.
Another big
theme of the book is that mental framing matters. Players and referees behave
differently when they frame a decision as a potential gain rather than a
potential loss. Tiger Woods putts more aggressively when he is putting for par
(a loss if he misses) than when he is putting for birdie (a gain if he makes).
Controlling for the distance and the ball placement—and a host of other
possible influences—the authors show that Woods is not only more likely to make
a par putt, but when he misses the shots are more evenly divided between long
and short. On similar birdie putts, he is more likely to be short. Even though
a stroke is a stroke is a stroke, Woods treats them differently because of the
gain/loss frame.
The authors
show the same effect in baseball with regard to 3–2 pitches. You might think
that there is no natural gain or loss frame for how a pitcher or a hitter would
think about a full count. But the authors inventively restrict their attention
to full counts that had started as either 3–0 or 0–2. If you are a pitcher and
had initially gone down 3–0, then battled back to 3–2, you are likely to frame
the next pitch as a potential gain. Conversely, if you had started out 0–2 and
then thrown three balls in succession, you’re more likely to think of the next
pitch as a potential loss. Can you guess how the frame affects the behavior of
pitchers?
The book also
sparkles when it comes to suggesting solutions to problems that I didn’t know
even existed. We learn that in NFL overtime games, the team that wins the
possession-deciding coin flip has a 61 percent chance of winning the game.
Instead of a coin flip, the authors suggest, coaches should submit bids for
where they would be willing to start on the field. The team that was willing to
start closest to its own end zone would get to start with the ball in overtime
first. I love the idea of replacing the arbitrary advantage of the coin flip
with an interesting strategic choice for the likes of New England Patriots
coach Bill Belichick to stew over.
In other areas,
I wish the book had called for more coin flipping. The book whetted my appetite
for evidence-based conclusions about sports performance—and crunching
historical data sets can only take us so far. Evidence-based medicine would
never operate in the absence of randomized trials, but to date there has never
been a randomized trial of sports strategy. We could test, for example, whether
a statistician could call better pitches than a team’s pitching coach: just
allow a statistical algorithm to control in a randomly selected sample of
at-bats. The absence of randomized trials suggests to me that there’s still a
lot of low-hanging empirical fruit. But all in all, Scorecasting does a great job in showing how much players, coaches, and fans can learn from
diving into the data.  |