June 26, 2011


Swing for the Fences: a review of Scorecasting: The Hidden Influences behind How Sports Are Played and Games Are Won by Tobias Moskowitz and Jon Wertheim (David Runciman, 6/30/11, London Review of Books)

Now here come Tobias Moskowitz and Jon Wertheim to clear up the mystery. Scorecasting is a book in what has become an increasingly familiar genre, a Freakonomics-style investigation into everyday phenomena that we take for granted but can’t explain. The two authors fit the requisite profile: Moskowitz is an economist with an interest in sport; Wertheim is a sports journalist with an interest in numbers; they are old friends. They follow the prescribed method: first take something people think they understand but don’t, then crunch some numbers, strip out the variables, throw in a few one-liners to keep your readers interested and voilà! – whatever you are left with is the truth, however improbable it sounds. Sport has always looked like ripe territory for this sort of approach, because there are lots of numbers to crunch and lots of prejudices to explode. But apart from baseball, which has its own well-established sub-genre of statistical myth-busters (known as sabermetricians), the sportonomics books have all been disappointing. Maybe sport makes it too easy: there are so many stats to play with, and so much nonsense is bandied about as though it were true, that it’s tempting to skip the hard work and simply line up the fish in the barrel. Scorecasting doesn’t do that. It is by far the most engaging book of its kind yet published, crisply written, extensively researched and full of surprises. The biggest surprise of all is home advantage.

So what causes it? First, Moskowitz and Wertheim rule out the conventional explanations, starting with the support of the home fans. How do you isolate the effect of the crowd on a team’s performance? They do it by comparing how well home and away players perform when faced with identical tasks, save only for the presence or absence of a hostile audience. Take basketball: when a player is fouled, he (or she) is awarded free throws at the basket from 15 feet. No one is allowed to interfere, apart from the home fans, who can do what they like to put off the opposition. If you’ve ever seen an NBA game in the States you’ll know this often includes shaking rattles and waving balloons from behind the basket. The result? Nothing. The stats show that away players perform just as well as home players from the free-throw line, despite all the barracking. The same applies to goal-kicking in American football, and penalty shoot-outs in our version. The home side has no better chance of winning at penalties than the away team. Home fans often think they can help the ball into the net with their hushed support, or keep it out with their whistling derision. It seems they might as well save their breath.

If it’s not the fans, maybe it’s the travel. Away teams often have to cross long distances (especially in the US), sleep in unfamiliar beds, and deal with all the discomfort of being far from home. This one is easy to disprove. The record of away teams across all sports is just as bad in local derbies, despite the fact that getting to the ground is no more inconvenient than for the home players. Everton’s and Liverpool’s grounds are less than a mile apart – but Everton are still much more likely to beat Liverpool when they don’t have to make the short journey to Anfield. The historical data back this up. Travelling conditions for top athletes have got immeasurably better over time – where once it might have been as slow and difficult for them to get around as for the rest of us, now it tends to be pampered luxury all the way. But their performances away from home have not got better at all. As Moskowitz and Wertheim put it, ‘the home field advantage is almost eerily constant through time.’ You can do what you like to ensure your players do not suffer all the little inconveniences of being on the road – they are still liable to let you down when they arrive. (The one correlation Moskowitz and Wertheim do find between travel and performance is for those sports where away teams are sometimes forced to cram games together on a single road trip, meaning they have a tighter schedule than their opponents. This is true for US college basketball, where away sides are often disadvantaged by having to rush from town to town while the home teams get a day off – and in college basketball home court advantage runs as high as 69 per cent. But here the test is European soccer, where there are no scheduling anomalies, and where home teams win almost as often.)

What about local knowledge? Every ground is slightly different, so perhaps teams take advantage of their familiarity with their home environment. Even football pitches vary: some are wider, some are narrower, some are blowy, some are sheltered, some are rough, some are smooth. The differences are most noticeable in baseball, where some teams play at stadiums that suit hitters, and others at stadiums that suit pitchers (it’s a question of size, shape and atmospherics). Yet even in baseball, Moskowitz and Wertheim find it makes no difference. Teams that play in hitter-friendly stadiums do not outhit their opponents by any greater margin than teams that play in pitcher-friendly stadiums. This despite the fact that managers can pack the team with sluggers, sure that they will play at least half their games in advantageous conditions. Knowing what you need to do well in your own yard doesn’t help you do it any better. Home advantage seems to be entirely outside anyone’s power to control.

It’s not the crowd, it’s not the travel, it’s not the stadiums, it’s not the players or the managers. So what’s left? Well, there are always the referees (or umpires as they are known in most American sports). And that’s who it is – Moskowitz and Wertheim say home advantage is almost entirely down to the officials. Players aren’t put off by the barracking of the home fans, but the umpires are. It makes sense when you think about it – if tens of thousands of semi-hysterical people were scrutinising your performance, you’d want to try to please them if you could, if only subconsciously. The away players have nothing to gain from the home fans – if they do well they’ll get abuse, if they do badly they’ll get mockery. But the officials can make the home crowd happy and then surreptitiously bask in the warm glow. Away players can’t alleviate the pressure of being in a hostile environment. Referees can.

Moskowitz and Wertheim find plenty of evidence to back this up. In football, it turns out that referees consistently award more injury time when home teams are losing, and less when they are winning (on average, four minutes in the first case and two minutes in the second, enough to make a difference in plenty of matches). Home teams get far fewer players sent off, and receive many more free-kicks. Maybe this is down to the fact that the home side simply plays better and the away players are reduced to desperate measures. But Moskowitz and Wertheim find evidence that crowd effects make a real difference. In the German Bundesliga, for instance, where many of the teams used to play in stadiums incorporating running tracks, putting the crowd much further away from the action, the bias referees normally show to the home side was cut in half. In the British, Spanish and Italian leagues, attendance also has a marked effect on the number of red cards shown to the visitors. The bigger the crowd, the more likely the away team are to end up with fewer players on the pitch at the end.

However, the most compelling evidence for referee bias comes from those sports that have introduced technology to check on the decision-making of the officials. In baseball, a system called QuesTec (similar to Hawk-Eye in cricket and tennis) now shows whether a pitch was in the strike zone or not (the area over the home plate between a batter’s armpits and his knees). Moskowitz and Wertheim have looked at a mass of data and discovered that when a pitch is clearly a strike, baseball umpires do not advantage the home hitters. Equally, when a pitch is way outside the strike zone, they call it against the pitcher. But when it’s on the edges, the home team were getting a large percentage of favourable calls. This shows two things. First, given the choice, umpires prefer to please the locals who are breathing down their necks (in many baseball stadiums almost literally). Second, they know what they are doing – they restrict their bias to areas where it won’t be so obvious (in stadiums that have installed QuesTec umpires have started to eliminate their home bias, now that they realise it’s there for all to see). Moskowitz and Wertheim find the same thing in ice hockey and American football, where the introduction of instant replay reviews showed that for close calls, and in tight games, the officials tend to favour the home team by a significant margin (calls against the away side are more likely to be corrected when impartial technology is called in evidence). Tight games are by definition the ones that can turn on one or two key decisions. And it appears that tight games are also the ones in which the officials go out of their way to help the home team. That’s enough for Wertheim and Moskowitz to finger them as almost entirely responsible for the phenomenon of home advantage.

It’s a lovely theory – simple, elegant and in tune with what most of us believe about human nature (and with what many fans have long suspected but never been able to prove about referees). There’s only one problem – it’s not true. I don’t doubt that referee bias has something to do with home advantage, but the idea that it’s the crucial determining factor is absurd. Just think about it – or rather, think twice about it. The first time you’re told it’s the referees you will probably go ‘aha!’, as I did. But the second time you’ll go ‘huh?’ Look at a football game. Yes, the home side does sometimes seem to get the benefit of the doubt from the referee, and yes, injury time does seem to go on for ever when Manchester United are playing at home – the image of Alex Ferguson consulting his watch as United push forward for a winning goal in the 97th minute at Old Trafford is probably the one that defines the Premier League. But why do the home side always seem more likely to score at the end? Why are they the ones pushing forward? Look, really look. It’s not just because the referee is letting them, it’s because something is making them play better. They believe.

Except that the data demonstrated that they don't believe, they know that the officials will fiddle the result.

Posted by at June 26, 2011 11:20 AM

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