By Tony Attwood
I like statistics, and use them a lot. But they have to be statistics that are realistically related to the real world. Consider this for example from Statsbomb
“Arsenal are conceding an eye popping 1.50 expected goals per match. The only five teams with worse defensive numbers than Emery’s team are Brighton, Burnley, Fulham, Huddersfield, and West Ham.”
Now to be clear “Expected goals” answers the question of whether a player should have scored from a certain opportunity. As a measure of how a player is doing it is quite good, because if players don’t score the number of expected goals then there is room for improvement. If they score every expected goal, then there is no room for improvement.
But jump sideways, if you can, and look at the league table organised by goals conceded.
Column 1 in the table below tells us the league position, column 2 the position if we only measured goals against, and column 3 the difference between the two. A blank means that there is no difference between their position on points and their position in term of goals against. A plus number means they are higher in the position on points than they would be if goals against counted, and a negative obviously means they are lower in the position on points than they would be if goals against counted.
If we counted goals against, Arsenal would be three places lower than they actually area, suggesting (to me if no one else) that the defence still needs improving – but that it is not in a catastrophic position.
|Lge Pos||Ag pos||Pos dif||Team||P||W||D||L||F||A||GD||Pts|
|14||16||-2||West Ham United||7||2||1||4||8||12||-4||7|
|15||17||-2||Brighton & Hove||7||1||2||4||8||13||-5||5|
Statsbomb conclude “A defense that doesn’t suppress shots, and also allows good shots is not a good defense.” Yes that is true. But not a disastrous defence if the club is winning matches. After all a club that won every game 10-9 would have the worst defence in the league and yet be champions. And although it would give George Graham heart attacks, I’d actually quite enjoy it.
The problem with each statistical measure is that it is only measuring one thing and football is not about one thing. For example Manchester City are not top just because of having the best defence in the league, it is because they have the best defence and best attack.
But there is worse to come in the Statsbomb analysis of because it says, of Arsenal, “They’re the same problems that Arsenal had coming into the season, and ones that new manager Emery was tasked with fixing. He certainly hasn’t been able to yet.”
However try this. Before the season began I put forward the notion that if Arsenal could keep their home form of last season (in which we were second only to Manchester City), but improve our away form back to its average in seasons before the last campaign, we would probably come third.
It is too early to say if we are actually doing that, but the fact is that after 19 away games in the league last season we had won 4. This season after 3 away games we have won 2. We are on track to hit that target of returning to our average away form of previous years. In 2016 when we came third, we won eight of our away games. That seems to me to be a good target to aim for and an analysis which has the virtue of being much simpler than expected goals.
The view is expressed that the defensive inadequacies have been there for all to see for years – all that is except Mr Wenger, and now seemingly Mr Emery have seen it. And yet if we had such an appallingly rubbish defence for so many years and if defence was the key indicator on which success could be measured that should show up in our history.
So I decided to look and see if the number of goals we concede relate to where we end up in the league. If they do they we should have a best defence at the time when we come highest in the league.
Our best defensive season in the last 20 years was 1998/9 with just 17 goals let in, and we came second, so it seems there might be a link. But in 1998 we won the league and yet conceded almost twice as many goals as when we came second.
In 2000 we came second and conceded a whopping 43 goals – our 15th worst defensive performance of the last 20 years. But we came second!
True two of our three worst defensive years in the last 20 seasons have been in the past two seasons when we have ended up 5th and 6th in the league. So that suggests the obvious is true, a bad defence leads to a lower position. But in 2012 we let in 49, our worst but one defensive year in the past 20 years and came 3rd in the league. So it doesn’t always follow.
In 1999/2000 we let in 43, just one fewer than the “disastrous” 2016/17, and yet we came second and no one was screaming that our defence was so awful that we needed wholesale changes.
Two years later we reduced the number of goals conceded by just seven and won the league.
|Season||Goals Against||Points||Lge pos|
Of course it is better to concede fewer rather than more goals, but it is possible to play in a style that commits players to attack, and leaves gaps behind so that the number of goals increases. But it can also lead to the number scored increasing, and indeed so does the entertainment level.
My conclusion is, beware simplistic techniques that just measure one thing, like goals scored or expected goals against. Football is not that simple.
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