The form book is less useful as a guide to local derbies than to other games

What hope is there for Everton and Fulham in their local derbies on Sunday? Perhaps a bit more than there would have been if they were playing opponents of the same quality from further away.

There is some evidence that in a local derby scores are more unpredictable. The best team win more often than they lose – but not as much more often as they should.

The form book, some people say, is torn up before a local derby. They are wrong. But you could fairly say that the form book looks a little bit dog-eared.

On Sunday there is a Merseyside derby between Liverpool and Everton, a west London derby between Chelsea and Fulham and a north London derby between Arsenal and Tottenham.

I studied Premier League derbies played in at least one of the 20 seasons from 1998-99 to 2017-18. I allowed each team no more than one rival club. So, for example, Tottenham’s rivals were Arsenal not West Ham, who did not have one.

I recorded the results of each derby and also the results of both teams against other Premier League opponents. In this way I identified what I called the best team in each derby. The best team were the one with better results against other Premier League opponents.

I then asked myself this question: if results against other Premier League opponents gave a fair indication of ability, what would I have expected to happen in each derby – how often would I have expected the best team to win, draw and lose?

My answer was that overall I would have expected the best teams to win 46 per cent of derbies, draw 29 per cent and lose 25 per cent. And what happened? The best teams won 43 per cent, drew 31 per cent and lost 26 per cent. The best teams won three per cent less often, drew two per cent more often and lost one per cent more often.

Every team have a range of possible performances. Perhaps the weaker teams raised themselves for derbies and gave an upper percentile performance more often than in other games. This might have been enough to get a draw from some derbies that in other circumstances they would have lost, and now and then to turn a draw into a win.

I also asked myself how many goals I would have expected each team in a derby to score and compared this with the number of goals they did score. The implication was the same. Overall the best teams scored more goals than the worst teams – but not as many more as I would have expected.

In spread betting supremacy terms, I would have expected the best teams in derbies to average 0.5 goals per game more than the worst teams. They averaged 0.4 goals per game more. The difference was a tenth of a goal. One tick, as the traders say.

Unlevel playing fields in the FA Cup

The second round of the FA Cup, which starts on Friday, may reveal some interesting truths about goals in football matches.

The number of goals in a match is influenced by at least two things: the difference in ability between the teams and the importance of the occasion. The smaller the difference in ability between two teams the lower the score is likely to be. And the more important the occasion is the lower the score is likely to be.

That is why there are more goals in the early rounds of the FA Cup.

Across the 25 seasons from 1992-93 to 2017-18 goals per game averaged 3.0 in the first round, 2.8 in the second round and dropped to 2.1 by the final.

The final is much more important than the first round. And the difference in ability between participants is typically smaller. So scores tend to be lower.

The second round features teams from League One, League Two and from below the Football League. When League One teams played each other goals per game averaged 2.6. When League One teams played League Two opponents goals per game averaged 2.8. And when League One teams played opponents from below the Football League goals per game averaged 3.2.

The greater the difference in playing level between the teams, other things being equal, the higher the score. More often than not, most goals in a higher-scoring game go to the better team.

Upsets, when they come, tend to be by a low score. Think of big upsets down the years in FA Cup finals. Wigan beat Manchester City 1-0 in 2013, Everton beat Manchester United 1-0 in 1995, Wimbledon beat Liverpool 1-0 in 1988, West Ham beat Arsenal 1-0 in 1980, Southampton beat Manchester United 1-0 in 1976, Sunderland beat Leeds 1-0 in 1973.

You can see the pattern. Upsets like these are compared with David slaying Goliath. David felled Goliath with a single shot.

Imagine a match in which the underdogs have a 25 per cent chance of scoring each goal that is scored. If there is one goal in the match there is a 25 per cent chance they will score it and win. If there are three goals in the match there is only a 16 per cent chance they will score most or all of them and win. If there are five goals in the match there is just a ten per cent chance they will win.

The more goals there are in a match the more likely it becomes that the better team will win. The optimal strategy for the worse team is to keep play tight and low-scoring.

Rich get richer at the World Cup

It’s the players, stupid.

Lloyd’s of London ranked countries at the last two World Cups by the insurable value of their squad. Each player’s insurable value took into account his wages, which were divulged by Sporting Intelligence, who tell the story in their Global Sports Salaries Survey 2018.

The highest-ranked country this year was France. They won. The highest-ranked country in 2014 was Germany. They won. That could be a coincidence. More telling was the correlation for all countries between rank and stage reached. It was better this year than in 2014 but overall it was strong.

At those World Cups teams played between three and seven games, which is not many. In any one game something strange can happen. As the number of games in a competition goes up so does the chance that the best team will get the best results.

The best teams are made up of the best players, and a good proxy for the ability of a player is how much they are paid.

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