Tag: goal difference

Premier League Points Efficiency

It would be tautological to say that you win in football by scoring more goals than your opponent. What is interesting is that scoring more goals and letting in fewer works across games in a season as well, as data from the English Premier League shows.

We had seen an inkling of this last year, when I had showed that points in the Premier League were highly correlated with goal difference (96% R square for those that are interested). A little past the midway point of the current season and the correlation holds – 96% again.

In other words, a team’s goal difference (number of goals scored minus goals let in) can explain 96% of the variance in the number of points gained by the team in the season so far. The point of this post is to focus on the rest.

In the above image, the blue line is the line of best fit (or regression line). This line predicts the number of points scored by a team given their goal difference. Teams located above this line have been more efficient or lucky – they have got more points than their goal different would suggest. Teams below this line have been less efficient or unlucky – their goal difference has been distributed badly across games, leading to fewer points than the team should have got.

Manchester City seem to be extremely unlucky this season, in that they have scored about five fewer points than what their goal difference suggests. The other teams close to the top of the league are all above the line – showing they’ve been more efficient in the way their goals have been distributed (Spurs and Arsenal have been luckier than ManYoo, Chelski and Liverpool).

At the other end of the table, Huddersfield Town have been unlucky – their goal difference suggests they should have had four more points – a big difference for a relegation threatened team. Southampton, Newcastle and Crystal Palace are also in the same boat.

Finally, the use of goal difference is used to break ties in league tables is an attempt to undo the luck (or lack of it) that would have resulted in teams under- or over-performing in terms of points given the number of goals they’ve scored and let in. Some teams would have gotten much more (or less) points than deserved by sheer dint of their goals having been distributed better across matches (big losses and narrow wins). The use of goal difference is a small attempt to set that right.

English Premier League: Goal Difference to points correlation

So I was just looking down the English Premier League Table for the season, and I found that as I went down the list, the goal difference went lower. There’s nothing counterintuitive in this, but the degree of correlation seemed eerie.

So I downloaded the data and plotted a scatter-plot. And what do you have? A near-perfect regression. I even ran the regression and found a 96% R Square.

In other words, this EPL season has simply been all about scoring lots of goals and not letting in too many goals. It’s almost like the distribution of the goals itself doesn’t matter – apart from the relegation battle, that is!

PS: Look at the extent of Manchester City’s lead at the top. And what a scrap the relegation is!

What Should Mexico Do?

If Mexico and Uruguay draw their last league game, then both of them go through to the second round irrespective of what France and South Africa do. However, on account of a better goal difference, Uruguay will qualify as group winners and face the second-placed team from Group B, while Mexico will qualify second and meet the Group B winners, likely to be Argentina.

Uruguay’s option is clear. Play for a draw. If Mexico go for a win, Uruguay should just sit back and try hit back on the counterattack (and in terms of players and style, they are very well equipped for that). Simple case of getting men behind the ball and putting gaaji.

Mexico’s strategy is not so straightforward. The “greedy” thing to do would be to play for a draw, in which case they will most likely end up facing Argentina in the second round (if you remember, Mexico went out last World Cup by losing to Argentina at the same stage). On the other hand, if Mexico beat Uruguay, they will top Group A and meet a potentially inferior team (Korea or Greece) in the second round.

As mentioned earlier, if Mexico go for a win, Uruguay will simply defend and play a counterattacking game which they are good at, so I don’t know if they are going to go for it.

Thinking about it, it comes down to Mexico’s payoff function. I’m sure their payoff is an increasing function of how far they progress in the tournament. However, we should be able to identify one particular “jump” in payoff – some kind of a discontinuity, where the payoff increases considerably for one additional round of progress in the tournament.

If this “jump” is for the second round, Mexico can afford to put Ranatunga Principle, get a peaceful draw against Uruguay and claim their “jump reward”.

If the “jump” is for the quarter-finals, however, then Mexico will want to take the risk at this round in order to get themselves easier opponents in the round of 16 (I’m assuming here that Mexico consider Korea or Greece as much easier opponents than Argentina).

If the “jump” occurs further down in the tournament, I think there is way too much randomness about their potential quarterfinal opponents (especially given the fuzzy results in Groups C and D) and opponents as hard as  (or harder than ) Argentina cannot be ruled out. Nevertheless, they would rather face one tough opponent than two (and I’m assuming here that no team is significantly “harder” for Mexico than Argentina) and so they should put fight to avoid Argentina and thus go for a win.

Considering that they have reached the Round of 16 with reasonable regularity in the last few World Cups, I presume that their “payoff jump” will occur later in the tournament. And based on the above reasoning that means they should go for a win against Uruguay, so that they can try avoid Argentina.

And it is on this thin thread that the French are hanging their hopes (though first they need to thulp South Africa, no easy task).