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How negativists don’t just avoid stats, they misuse them too

By Tony Attwood

In an earlier article I was pointing out that the first eight games of the season don’t provide any sort of accurate prediction as to what will happen during the rest of the season.   Quite simply there are far too many variables in Premier League football, for eight games to be much of a guide as to what will happen in the remaining matches.

This is however the exact thing that many blogs and journalists seek to do: they try to suggest that by looking at what has happened so far, they can determine in detail, what will happen by the end of the season.

By way of example we can have a look at Lastwordonfootball – a blog that has proclaimed that, “Arsenal fans should be worried about the underlying statistics,” concerning the season so far.

Now my last piece suggested that there is no real link between Arsenal’s performance in the first eight games of the season and where they will actually end up – and at one level the “Arsenal fans should be worried” article agreed with this.  For this piece says…

“Arsenal sit third in the Premier League during this international break. They are also just one point removed from second place, occupied by Manchester City.”  But then comes the bad news for “the underlying statistics suggest that their league position is anything but safe.”

My position was that the statistics from the first eight games don’t tell us much at all, in that they are no guide to where the clubs will end up.  But this article says the opposite – that the stats do tell us something and it is bad news.  And the source of their information is not the actual real live league table but the notorious xG – which as the site says “measures how many goals a club should score from the chances they create.”   In short a hypothesis.

The position they set out is that, “Out of the big six clubs this season, Arsenal have created the second fewest xG, 11.75. While Tottenham Hotspur‘s 10.99 is worse, it is very far off xG leaders [Manchester] City, sitting on 25.55 xG.”

Now to make sense of this we need to know what xG actually means, and this explanation from an article in the Daily Telegraph is as good as any….

So let’s have a look

Club Expected goals Actual real life goals Ratio
Arsenal 11.75 13.00 1.11
Manchester City 25.55 27.00 1.05

So Arsenal are scoring more goals than expected, and they are doing it a little bit more than Manchester City.  But what is going wrong is that they are not creating enough chances.  If they did create more chances they would get even more goals.

And in fact we don’t need xG to see that.  What we need to do is look at the number of goals scored this season.  Here  is the league table based only on goals scored

1 Manchester City 8 5 1 2 27 9 18 16
2 Liverpool 8 8 0 0 20 6 14 24
3 Chelsea 8 4 2 2 18 14 4 14
4 Leicester City 8 4 2 2 14 7 7 14
5 Tottenham Hotspur 8 3 2 3 14 12 2 11
6 Arsenal 8 4 3 1 13 11 2 15

Arsenal’s goal scoring is considerably lower than the top two and five behind Chelsea so quite clearly we need to find a way of scoring more goals.  And that in a situation in which we are already scoring more than might be expected.

So should we have a better centre forward?   To answer this let us have a look at Auba’s results in relation to others in the Premier League this season…

  • 1: Tammy Abraham 8 goals
  • 2: Sergio Aguero 8 goals
  • 3: Pierre Emerick Aubameyang 7 goals

So Auba is the second highest scorer in the league, and given that, it seems a little harsh to start blaming the predicted forthcoming demise of Arsenal on him when he is the second best goalscorer in the league.

Now the article says, “Arsenal are overly-reliant on Pierre-Emerick Aubameyang. For a club to stay near the top of the table while creating so few chances, they need a world-class finisher who will score far more than he misses.”

That’s true, and oh, hang on, that’s what we have.  Actually what we also need is a second goal scorer – which we also have in Lacazette, who has been injured of late.

OK so it can be argued that we need further cover, and oh look, that is what we have in Martinelli.  Still young, but an absolute blast on the pitch.

Yes but really is that it?   Surely Arsenal needs someone else.   Well, ok we have Joe Willock who has scored three goals at a rate of 79 minutes per goal.  And we have Eddie away on loan who could well come back next season even sharper.  Or maybe sooner given that Leeds are not giving him many games.

Perhaps realising that the argument is not just thin but transparently wrong the writer shifts the emphasis to Expected Goals Against (xGA) and noted that we have a dodgy defence.

Except that until now we have not been playing our defence, but our backup defence.  Now we have that defence coming back, and after the break it should be there in all its shining glory.

But hang on, if until now we have had a dreadful defence, a mediocre attack, and we are not scoring the expected goals we should be, surely we should be sinking fast down the league.  And yet we are third.

And we have Lacazette to return, 75% of the defence to return, and some amazing youngsters coming through.

Third with four great players returning sounds rather good to me.  And the expected goals analysis actually does nothing to undermine this notion.

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