The Football Brain: Intellectual Part of the Game
The blog for deeper understanding of football. Enjoy.
Saturday, December 20, 2014
Premier League: who will improve in the second part of the season? Part 2.
Thursday, December 18, 2014
Premier League: who will improve in the second part of the season? Part 1.
It often happens that some teams perform
better in one half of the season then in the other. Sometimes it is related to
injury crises, sometimes it happens due to big winter signings (or losing
players), sometimes there is simply a hot (cold) streak, for which it is hard
to find a particular reason.
But sometimes it is just being (un)lucky.
What I will try to do in this article is to find an indicator that shows that a team concedes more or less goals than it should.
And for that reason I will use a very simple statistics: goals
conceded per shots on goal allowed.
It is fair
to say that the average number of shots needed to score almost does not
fluctuate from season to season: in 2012/13 it was 10,16 shots per goal, in
2013/14 – 9,98; this season it is exactly 10 shots per goal.
Also,
nothing indicates that this number has something to do with the quality of
defense or overall strength of the team. Here is, for instance, data for
2012/13:
I assume that +/- 1,5 shots per goal is normal fluctuation, while more of that signifies that something is going on. If there exists something systematic that makes a team concede from more/less shots on goal, then it should also translate into next seasons. Let’s look at the season 2013/14 then:
We can see several usual suspects here: Chelsea and West Ham on the positive side; Tottenham and Southampton on the negative. It is improbable that they are simply unlucky for two consecutive season, so it must be something else that makes them concede from more or less shots. What can be that?
1)
The goalkeeper. It is easy to imagine that Petr
Cech is responsible for some crucial saves that others would not have done,
therefore decreasing the total of goals conceded. But look at the difference:
in 2013/14 with 391 shots allowed, Chelsea were expected to concede 39 goals,
while they actually conceded 27. Can Cech single-handedly save the third of
goals? Were Joe Hart or David de Gea so much worse that they did not come even
close to him? It is hard to believe that.
2)
Fearsome defense. How about that for a narrative:
Chelsea’s opponents were so hopeless to come close to Chelsea’s goal through
Terry and Cahill that they were trying to score from distance, meaning that
each shot had a lower probability to result in a goal. No, I don’t like it
either.
3)
Style of play. It may have something to do with
style of play, something that is not measurable or noticeable. For instance, Chelsea and West Ham may give
opponents more freedom outside the box, encouraging them to shoot from there
more often, while Tottenham and Southampton limit opponents’ shooting from
distance, but allow more clear-cut opportunities.
Whatever it
is, if we look at this season and see that Chelsea, West Ham, Tottenham and
Southampton do not go in line with the rest of the league, we will not
attribute it to random fluctuations. And here is the data for 16 games of this
season:
Since
sample size for this season is much smaller, I raised the bar of normal
fluctuation to +/- 2, which allows me to make three predictions for the rest of
the season.
1. Arsenal are unlucky and will improve
defensively.
It is an
easy one, because the current statistics is ridiculous. Allowing 4 shots per
game less than Stoke, they managed to concede as many goals. Arsenal have been
“neutral” in the last two seasons, so it is safe to say it will take more shots
to score against them in the future.
2. Manchester City are lucky and will
deteriorate defensively.
After 16
games, Manchester City conceded 3 goals less than they should have done from
the number of shots they allowed. Being just in the green zone at 12,1 shots
per goal, they are actually not very far away from their 2012/13 record (11,6). Last season, however, Manchester City were below average (9,7) suggesting that, unlike Chelsea, they do not possess black magic and will regress closer to the
league average.
3. West Bromwich are unlucky and will improve
defensively.
Let me
rephrase it. West Brom are very
unlucky and definitely will improve
defensively. It takes less than 6,9 shots to score against them – unless you
really hate Ben Foster, it is hard to develop a narrative that would explain
it. From 200 shots, they conceded 29 goals, 9 more than they should have. 10th
in the league by shots allowed, they are second-bottom by goals conceded –
better only than QPR.
You disagree with my predictions? I can bet on them.
You disagree with my predictions? I can bet on them.
In the next article I will conduct a similar
analysis on goals scored.
Wednesday, December 17, 2014
Chelsea winning the quadruple is as likely as Liverpool relegating to Championship
After a comfortable win over Derby County
in the League Cup quarterfinal, Jose Mourihno and Cesc Fabregas had a little
disagreement over their team’s chances to win nothing less than quadruple this
season. The Spaniard, probably encouraged by lack of resistance from
Championship opposition, said that Chelsea “have all what it takes”, while the
manager insisted that “it is impossible”.
What is the true probability of Chelsea winning
a quadruple or any other combination of trophies, as of December 17th,
2014? To derive probabilities, I used bookies’ coefficients (if someone has
better estimations, which is confirmed by a long record of beating bookies,
please let me know: not only will I use it for this and similar post, but I
also will invest money in your strategy).
Monday, December 15, 2014
How much success can money buy in football?
This article presents relationship between wage bill and performance of Premier League teams in 21st century - starting with the season 2000/01 and until 2012/13 (the latest data available). Just in case you don't want to go through the whole article (full of numbers, I must warn), the bottom-line is the following: money may not guarantee the success, but it buys most of it - just above two-thirds, to be precise.
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