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August 2, 2013

Diego Costa Dissected

By Colin Trainor

So Diego Costa was all the rage on my Twitter time line last night following Liverpool’s reported £21m bid for the Brazilian Atletico Madrd striker.
Bar one or two notable exceptions, the news has been welcomed with great fervour, especially by Liverpool fans.

In such a situation it would be rude not to run the Statsbomb eye over what I presume to be Liverpool’s intended replacement for Suarez.

Statistics

First off, let’s start with a look at his stats for last season.  To aid comparison I have added his numbers to the recent data that I pulled together for my Chelsea strikers piece.

(The table is interactive and it can be sorted by the user, it is a wide table but the columns can be scrolled across.)

OK, so I know that he wasn’t Top Dog at Madrid, that honour went to Falcao, but those per 90 numbers aren’t great.  After slating Torres in yesterday’s article for his subded numbers I’m surprised to see that Costa’s shots and shots on target per 90 are on a par or worse than Torres’ figures.

However, what Costa did much better than Torres is convert the chances he is presented with.  This is why his goals per 90 of 0.44 beats Torres’ 0.28 out of the park.

On the downside, his turnover numbers are really bad.  I have created a metric “Turnover per SoT” and this could be subtitled the “Frustration Measure” as it quantifies the numbers of lost possession in terms of the shots on target a player had.  The thinking here is that you could tolerate a lot of lost possessions if, on balance, the player manages to strike a lot of efforts on goal as the trade off is worth while.

You can see that Costa is even more frustrating that Torres, as his 59 turnovers dwarf the 23 shots he put on target.  Costa’s Frustration Measure is more than double that of Ba and Lukaku.

I had a look at Suarez’s Frustration Measure, and remarkebly his is just 1.14 (79 tournovers and 69 SoT).  That demonstrates just how high Costa’s number of 2.56 is.

ExpG Measures

If you haven’t seen the ExpG and ExpG Eff metrics yet please take a quick look at my previous post (here) where I give an explanation of these new metrics.

Costa’s ExpG Eff of 1.09 marks him out as a pretty neat finisher.  This means that he has scored 9% more goals with the chances he had than an average player would have done.  For information Suarez posted a number of 1.08 last season.
His Average ExpG value per shot was 0.18.  You can see that this was higher than the figures posted by the 3 Chelsea players meaning that the shots he takes are of better quality.  Again for info, Suarez’s Average ExpG per shot was just 0.11.  This clearly demonstrates the poor shooting choices that Suarez made last season (and undoubtedly even before then as well).

So what do we make of his stats?

I’m surprised at how quiet he was in terms of the positive stats.  What he did, he did well, but given the Twitter praise that was being heaped upon him I expected to see higher figures being posted.
His strength seems to be in hitting the target, albeit on average the shots that he took on were fairly routine.  Of course, this canny choice of shot selection is a skill in itself but his ExpG Eff of “just” 1.09 means that he didn’t shoot the lights out.  I would therefore conclude that his accuracy was at least partly attributable to his shooting positions.

He looks like he will be a frustrating player to support and play with due to his enormous amount of lost possessions.  Having 2.5 times more turnovers that shots on target is a pretty poor figure.

Shooting Positions

Let’s look at his shooting positions:

CostaShots

The key at the foot of the chart should help explain things, but in summary green = goal, blue = save and red = miss or block.  The solid colours are shots and the checked dots are headers (he took no direct free kicks).

He appears to favour the left side of the pitch with a lot more of his shooting action coming from that left side.

7 of his 10 goals came from inside the 6 yard box, with the other 3 goals also coming centrally from well within the confines of the penalty area.

5 of his 10 goals were headed attempts.  In fact, heading appears to be one of his strengths as his 5 goals came from just 14 headers.
This superb conversion rate of 36% was the highest across the Big 5 leagues last season for players with at least 14 headers.
To provide some context; Postiga converted 19% of his headers last season, Kießling 16% and Negredo achieved 13%.  OK, so Costa’s headers are from prime heading positions but he obviously has a decent technique to achieve those accuracy and conversion rates.

As was expected from the shooting stats we observed at the top of this piece, his shot locations were smart with only 3 shots of the 50 he took coming from outside the penalty area.  In terms of his choice of shooting locations, Diego Costa certainly has an entirely different modus operandi to Luis Suarez.
If you were being a little critical you could argue that he didn’t score with any shots that weren’t straight in front of the goals and within fairly close range so perhaps he may lack that little spark that great strikers possess.

Shot Placements

CostaPlacements

I like his shot placements.
The majority of his on target shots were kept low and he wasn’t afraid to try to find the bottom right hand corner.  The total absence of shots that would hit a stationary goalkeeper’s torso or head is a nice aspect of his shooting.

Summary

If lost possessions could be ignored, Diego Costa is efficient but quiet.   However, they can’t be and he seems to be extremley wasteful in terms of lost possessions.
Purely from a shooting point of view, whatever he does he does well.  He also has the benefit of  providing a significant heading threat to any defence he comes up against.

However, I can’t help but think that he is missing a little something that would make him special.  His lack of involvement in an attacking sense is somewhat disappointing and, personally, I would have liked to see some more fireworks from his shooting, and certainly less lost possessions.

But perhaps, as we are talking about Liverpool an efficient, quiet striker is what is required for the new season, albeit they would probably prefer one that is less frustrating than their current striker.

EDIT – I have created a short piece where I justify why I’m not looking at Costa as a winger http://statsbomb.com/2013/08/costa-average-positions/

Article by Colin Trainor