Liverpool’s Defensive Weakness

When compiling the recent article that I posted where I looked at where teams conceded shots from I came across some interesting findings in relation to Liverpool.

We’ll go for a slight recap and start with the good news for Liverpool; as a defensive unit they were extremely successful at forcing teams to take shots from poor shooting locations:

ShotsConceded

So good were Liverpool in forcing teams to shoot from non optimum positions that they only permitted 18% of shots to come from what I have defined as the Prime location.  As you can see, this value ensured that they led the league quite comfortably in terms of this particular metric.  Of course this fact raises potential questions around how Reina performed in keeping out shots given the great job that his defence did in front of him.  That question can remain unanswered until another day.

I want to look at another feature of Liverpool’s defending that caught my eye; which side of the pitch did the conceded shots originate from.

Background

It surprised me a little to see that 47% of all the shots (excluding headers and penalties) in the Big 5 European leagues last season came from left of centre, 19% were straight on and just 34% came from an area to the right of centre.  I can only presume that the large number of shots from the left side of the pitch is due to the predominate use of the right foot when shooting.  It is obviously much more natural for right footed players to shoot from the left hand side.

From a defence viewpoint the image below shows the areas of the shooting zone that I am defining as right, left and centre of defence:

SidesTemplate

Which side of the pitch did the Premier League teams concede shots from last season?

EPLSidesConcede

Remember, this table is from a defensive viewpoint, and has been sorted in descending order on the Right hand side.

Although there is a heavy bias to all teams conceding shots from their right hand side (this is obviously the other side of the coin to more shots being struck from the attacker’s left side), Liverpool allow a greater proportion of shots to come from their right hand side than any other team in the league.  The league average for conceding shots from the right hand side was 47% but Liverpool allowed in excess of 54% of their shots to be struck from their right hand side.

Their figure conceded down the right of 54.4% is more than 2.5 standard deviations from the league mean which is significant at a level of 1%, or in layman’s terms “there is definitely something happening that causes so many shots to come from Liverpool’s right hand side”.

Is Glen Johnson at fault?

The first possible explanation for this fact that jumped into my head was “Glen Johnson”.  Although Glen Johnson offers Liverpool great attacking potential, in fact he averaged 1.5 shots per game last season which put him just behind David Luiz in terms of attempts by defenders; perhaps these attacking forays come at a price to Liverpool.
I am aware that Johnson didn’t play every game last season and I haven’t yet went to the trouble to separate the shooting statistics for the games that he did play versus the games that he missed.

Whatever the explanation it certainly seems that Liverpool is much more open on their right hand side than any other team in the Premier League.  It’s safe to assume that this fact won’t have gone unnoticed by Premier League managers.

I’m interested to hear any other possible explanations for the heavy bias of shots conceded down Liverpool’s defensive right side.

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Where did teams concede shots from?

All the shooting location analysis work I have done so far has concentrated on the attacking sides, so I thought it about time that I looked at the other side of the coin; how teams defended.  In my previous article I concluded that headers are a lot less dangerous to concede than shots.
With that in mind, and for the purposes of this article, I thought I would strip out headers (as well as penalties), and thus we are left with just non-headed attempts on goal.

As before, in order to aid analysis, I have divided the shots conceded by each team into four different areas which are colour coded as per the legend below.

template

Here is the summary of shots conceded by each team in the 2012/13 Premier League season:

ShotsConceded

I have listed the number of shots that each team conceded, and then showed the percentage of shots that each team allowed in each of the four areas.  The last two columns show the combined proportion and number of shots that each team allowed in the two best areas for shooting, the Prime and Secondary areas.
The table has been sorted by Prime and Secondary Percentage in ascending order.

Liverpool

The team that sits atop of this table is Liverpool.  They permitted less than 55% of the shots they conceded to be struck from the Prime and Secondary areas, and they were the only team in the league to allow less than 20% of their shots conceded to come from the Prime area (18%).
There is no getting away from the fact that Liverpool put in a tremendous defensive performance during the season just ended. For this they should receive a lot of credit.

Stoke

The appearance of Stoke or “PulisBall” as described by MarkTaylor in second position will come as no surprise to analytics aficionados.  Pulis puts (or should that be “put”) great store on his team taking shots from good locations and preventing the opposition from doing likewise.

QPR

QPR are interesting.  For a team that struggled so badly I was surprised to see them sitting as high as 5th in this table with just over 62% of shots conceded from the Prime and Secondary areas.  Of course, the quantity of shots they allowed at 489 would somewhat counteract that last statement.

Tottenham

Although Tottenham appear towards the bottom of this table with a relatively poor 66% of shots permitted to be taken from the Prime & Secondary positions the fact that they conceded a league low 297 shots resulted in them conceding the fewest number of shots from the two most attractive shooting areas.

Reading

From a defensive viewpoint Reading stank the place out.  At 591 they conceded the highest number of shots and the positions they allowed those shots to be taken from were just as horrendous.

Hopefully the above table will serve as a useful point of reference for anyone that wants to see how a particular team did in terms of the number, or more importantly, location of shots they permitted last season.
I’m also that sure this won’t be the last time that I look at the type of shots that teams permitted.