Scorecasting (21 page)

We didn’t find that to be the case.

Much as broadcasters talk about those poor teams from the tropical precincts—say, the Miami Dolphins and San Diego Chargers—faltering in the “frozen tundra” of Lambeau Field in Green Bay or thermally challenged lakeside stadiums in Buffalo and Cleveland, climate, we’ve found, is largely irrelevant. If NFL teams are built to take advantage of their home weather, we should observe cold weather teams winning disproportionately in cold weather games. We also should observe teams playing poorly when venturing to markedly different climates. Finally, we should observe that “domed teams,” because they play in climate-controlled chambers, are simply insensitive to home weather. Think of this last situation as a placebo test. If the control group experiences similar reactions even though they weren’t administered any treatment or medicine, you know it wasn’t the drug but something else that caused their reactions. Similarly, if domed teams seem to perform differently depending on the outside weather, it must be something else influencing the results. For example, just as the weather tends to get worse late in the NFL season in December, teams may play better at home late in the season, having nothing to do with weather at all.

After studying data from every NFL game from every season between 1985 and 2009—nearly 6,000 games—and matching those games to the outside temperature and wind, rain, and snow conditions, we found that cold weather teams
^*
are no more likely to win at home when the weather is brutally cold, nor are warm weather teams more likely to win at home when the temperature
is awfully hot. And the home winning percentages for dome teams immune from extreme weather conditions—our placebo test—do not vary with the weather any more than they do for cold and tropical weather teams. Even looking at the most extreme cases, when a warm weather team has to play in extremely cold weather or a cold weather team plays in humid and hot conditions, there is little to no unusual effect. Contrary to conventional wisdom, weather gives a team no additional home advantage. Either teams are not built to suit their home weather conditions or, if they are, it doesn’t seem to have much effect on the outcome of games.

What about baseball? After all, not only do the playing conditions vary but—one of the sport’s great appeals—each stadium is unique. Don’t the home players have an advantage, as they’re more familiar with their ballpark’s idiosyncrasies? Don’t teams stock their rosters with players who are better suited for their park’s features? And couldn’t this influence the home field advantage in baseball?

Yes and no.

There’s no question that the Boston Red Sox, for instance, have an advantage playing at Fenway Park. The Sox outfielders know the Green Monster, the notorious 37-foot-high left field wall, the way Thoreau knew Walden Pond. Unlike the opponent, they’re well acquainted with caroms and angles and the effect of the wind. (There’s even an ersatz Green Monster scheduled for construction at the Red Sox spring training facility so the organization’s minor leaguers can familiarize themselves with the wall’s distinctive features.) Similarly, Sox hitters know that although the Green Monster is high, it’s also deceptively shallow—barely 300 feet from home plate—and they adjust their swings accordingly. Surely this has an effect on Boston’s home winning percentage.

You might also surmise that baseball players are familiar with the unique optics of their home park. The home batters see the ball better; the visiting pitchers exhibit less control. But we already know that once we’ve controlled for other factors—pitch count, game situation, and so forth—players don’t hit the ball
appreciably better at home and pitchers don’t throw appreciably less accurately on the road. Thus, that can’t be the reason home teams win more games.

What about the notion that baseball teams win more games at home because they tailor their rosters to the idiosyncrasies of their ballparks? The teams that play in parks with, say, shallow right field porches recruit more left-handed hitters. The teams with uncharitable dimensions recruit superior pitchers and speedy outfielders. How much does this affect the home field advantage?

Since it would be impossible to consider every ballpark and how different types of players might be better suited to each, we looked at the most obvious case in baseball and the one likely to have the biggest impact: “hitter-friendly” ballparks versus “pitcher-friendly” ballparks. The Sabermetrics community helped us identify which ballparks historically were hitter-friendly, using total number of runs, hits, extra-base hits, and home runs produced in each ballpark by all teams each season. We then asked: Do teams from hitters’ parks outhit their visitors by more than teams from pitchers’ parks do? If teams from hitters’ parks are being stacked with sluggers, we should see them outhit their visiting opponents by a wider margin than that of teams from pitchers’ parks. Yet we don’t. Teams from hitters’ ballparks outhit their visitors by the same amount as home teams in pitchers’ parks do—same differences in batting average, home runs, doubles, triples, slugging percentage, and runs created. We even found this to be the case when a hitting team plays host to a team from a pitchers’ ballpark, where you’d expect the widest difference.

We also looked at how teams from hitters’ ballparks play
away
from home. If their lineup is stocked with hitters, they should hit better than other teams no matter where they play. (Plus, by looking at other ballparks we also remove any other home advantages, such as crowd, familiarity with field of play, and travel.) But we found that teams that play at home in hitters’ ballparks hit no better on the road than teams that play host in pitchers’ ballparks do when they’re on the road, even going so far as to control for
the same stadium. That is, the Colorado Rockies (who play in a hitters’ park) hit as well as the
New York Mets (who play in a pitchers’ park) when they each play in Busch Stadium in St. Louis.

All this evidence indicates that either teams aren’t stacking their rosters to suit their home stadiums or, if they are, it’s not making much of a difference. Bear in mind that the home field advantage in sports is lowest in baseball. Even if “roster tailoring” is a factor in some cases, it doesn’t get us very far in explaining the home field advantage phenomenon overall.

We should add that deception and “dark arts” don’t seem to be much of an explanation for the home advantage, either. In past eras, it was different. In 1900, for instance, a shortstop on the visiting Cincinnati Reds noticed that the Phillies’ third-base coach stood in a puddle each inning. When the shortstop investigated, he found that under the puddle was a wooden box. It turned out that a Phillies backup catcher sat in the outfield bleachers armed with high-powered lenses and stole signs from the visiting team. Then, using a buzzer that was connected to the wooden box with wires that ran under the field, he used Morse code to convey the pitch to the third-base coach. The coach then relayed the information to the batter. Little wonder the Phillies won two-thirds of their games at home and fewer than half on the road.

Through the years, other home teams have used elaborate plots to steal signs from the visitors. For years, home groundskeepers in baseball would water the field into a bog when speedy visiting teams were in town. The
Boston Celtics were notorious for jacking up the heat in the visitors’ locker rooms so that halftime resembled a session in a sauna. The
University of Iowa football team once ordered the visiting locker rooms painted pink, hoping it would make the opponent feel passive or emasculated. It’s unclear if any of this worked—and it probably didn’t—but because of the standardized league rules, the stiff deterring punishment for cheating, and surveillance technology, it would be hard to pull off this kind of skulduggery today.

So let’s take stock of all we know: When athletes are at home, they don’t seem to hit or pitch better in baseball, shoot free throws better in basketball, slap goals better in hockey shootouts, or pass better in football. The home crowd doesn’t appear to be helping the home team or harming the visitors. We checked “the vicissitudes of travel” off the list. And although scheduling bias against the road team explains some of the home field advantage, particularly in college sports, it’s irrelevant in many sports. The notion that teams are assembled to take advantage of unique home characteristics isn’t borne out, either.

Yet if home teams are winning more games so consistently, players on those teams surely must be doing
something
better than their opponents. What else is giving the home team its sizable edge?

Thanks to the quirks of the NBA schedule, the Blazers and the Spurs played again four nights later. Duncan, San Antonio’s exceptional big man, had regained his health and was back in the lineup. If the Spurs had beaten the Blazers by 15 points when he was on the bench, surely they would crush them with Duncan in the game. Right?

But this time the two teams played in Portland. This time the Blazers would have the exuberant PA announcer, the dance teams, the 20,000 partisan fans. This time the Blazers shot more free throws. This time the Spurs committed more fouls and turnovers. This time the Blazers won 102–84, a whopping 33-point swing from their game only 96 hours earlier.

Maybe these athletes and coaches are right, after all, to adopt a defeatist attitude when heading off on the road.

But why
?

SO, WHAT
IS
DRIVING THE HOME FIELD ADVANTAGE?