Will a defensive-minded World Cup mean a defensive-minded Premier League season?

August 13, 2010

Spain goalkeeper Iker Casillas holds the World Cup

ZM was planning to publish an extended article about how the defensiveness of the World Cup could result in a more defensive Premiership season.

However, Jonathan Wilson got there first and covered everything. The last time we had this was 2004, the year of the underdog – Jose Mourinho’s Porto won the Champions League and Otto Rehhagel’s Greece won the European Championships by playing defensive-minded football. The start of the next Premier League season was the most negative in the short history of the division, with Mourinho summing it up with his legendary ‘park the bus’ comment following a goalless draw against Tottenham.

That’s just one example, however – a couple of defensive victories clearly inspiring teams. But how much are Premiership teams influenced by tactics at major international tournaments? Quantifying ‘defensiveness’ is not easy, but here’s an attempt at finding a correlation.

There’s two sets of data we need. The ‘outcome’ is quite easy to find appropriate data for – in terms of how defensive-minded the Premier League seasons are, we can use a simple ‘goals per game’ statistic. Not a perfect measure for judging ‘defensiveness’ – if we were being more thorough, we might use a multitude of factors including shots on goal, shots on target etc. But in the interests of simplicity and accessibility to data, we’ll use goals per game ratio.

Finding an appropriate set of data for the international tournaments is a little more difficult. We could use a simple goals per game ratio for these tournaments as well, but this would probably miss the point in what we were trying to achieve. In 2004/05, the Premier League sides were not chiefly inspired by Euro 2004 itself, simply by the winners of it, Greece. Therefore, we have to take account of the ‘defensiveness’ of the victorious sides, as well as the simple goals per game ratio of the tournament as a whole.

Therefore, there’s a need to create a new set of data, in a move which is probably riddled with statistical inaccuracies. But, again, for the sake of simplicity, let’s use (a) the goals per game ratio of the international tournament as a whole, and (b) the number of goals scored per game of the champions of that tournament, and multiply them. So, for 2006, we take the overall goals per game (2.3), the number of goals Italy scored per game (1.7), and get a ‘defensiveness factor’ of 3.93.

Then, because we have to consider two Premier League campaigns after each international tournament, we’ll take the subsequent two seasons, and find the average of their goals per game ratio. So, to consider the influence of the 2006 World up, we take the goals per game ratio from 2006/07 (2.45) and from 2007/08 (2.64) and end up with an average of 2.55.

And then, we plot them onto a line graph with two y axes, and get a result like this:

Or, if you’re more of a scattergraph fan, here you go:

From the line graph, we have little of interest towards the beginning of the Premier League – perhaps when teams were more tactically naive, or simply because of the smaller international tournaments (and therefore smaller and less reliable sample size).

But, from the start of the millennium, we find a much more interesting pattern – every time the blue line goes up, the red line follows, and every time it falls, we have the same effect. 2004 saw the lowest defensiveness factor for the international tournament, and sure enough, we had a defensive-minded couple of Premier League campaigns.

The scattergraph is slightly less detailed because of its relative simplicity, but probably comes out with a more interesting-looking correlation.


Statistically reliable? Probably not. We haven’t considered the factor of extra-time in the major international tournaments, for example, and our method of finding a ‘defensiveness factor’ might not be strictly correct. We haven’t looked at the influence of Champions League winners, and there could be an argument about how much goals-per-game actually sums up how defensive football is.

Nevertheless, there’s a decent pattern in the past few years. We can’t prove that correlation is the same as causation – but if it is, then the international tournament with the lowest ‘defensiveness factor’ is a little worrying for fans of attack-minded football.

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