The book, or at least the review, is concerned with the mystery of home advantage. Why do home teams do so much better in sports fixtures than away teams? Runciman says:
Take any European football league in which all the teams play each other twice in a season, once at home and once away. Add up the total number of home victories and compare it to the total number of away victories. The ratio will be at least 60:40 in favour of the home sides (often it’s more: in the English Premier League home advantage currently runs at around 63 per cent, in Spain’s La Liga it’s 65 and Italy’s Serie A it’s 67).According to the review, Moskowitz and Wertheim see the explanation as lying in the influence of the crowd - not on the players, but on officials. Close decisions go they way of the home team.
Runciman doubts this. Home teams do so much better that if it were down to the refereeing or umpiring then it would be blatantly obvious that they were being favoured. And it isn't. There is some evidence from baseball, where Hawkeye-style technology has been introduced, that home teams are favoured when a marginal decision has to be made, but the effect is marginal and nothing like enough to explain the full discrepancy.
And it's not the travel or knowledge of the ground either, argues Runciman. Instead:
Home advantage is much more complicated and much more mysterious. It depends on a range of factors that are effectively impossible to quantify.A cop out? Maybe, but it is a fascinating review and one of those unquantifiable factors turns out to be Jose Mourinho's overcoat.