10 June, 2016

Euro ruthless ref

By Shijith Kunhitty

Here's an analytical look at the men who decide football games with mere whistles and gesticulations.

Euro 2016 is coming up in a few days, and there’s no shortage of coverage about players, tactics, managers etc. (The Guardian’s Euro 2016 section is particularly good). But one thing a lot of the articles will be missing is a look at the one person with the most influence on the outcome — the referee.

The thing about refereeing is that it’s one of the most high-profile but completely thankless jobs around. If you do everything right, no one ever takes notice, but make one mistake in a crucial match and the whole world is on your case.

So refereeing is a high-pressure role that not everyone can handle. The 18 who will be going to the Euros are some of the best referees Europe has to offer.

One of them, for example — Mark Clattenburg — had the privilege of officiating the FA cup final and the Champions League final in the span of a week. (Yup, he was the one who went full lizard tongue at Real Madrid defender Pepe!)

So, how have these referees officiated over the years? What are their styles? Are some of them the kind to issue yellows early and often — in order to stamp their authority? Are some of them the kind to avoid early bookings and let the game flow, taking the card out only if they really need to?

Based on data from Soccerway.com for around 5,000 matches over the past 14 years, with at least 200 matches taken for each Euro 2016 referee, we can understand how these officials have been dealing out yellow and red cards over their careers.

We were able to figure out four different things:

a) who books people the most;

b) who takes out cards the quickest;

c) who most gives out second yellows to send people off; and

d) who gives out multiple cards in a match the most

Curiously, the answer to all the questions is the Spanish referee, 45-year-old Carlos Carballo. You may not know him by name, but if you watch the Champions League regularly, you will most definitely recognise him.

Now on to the analysis.

Carballo has officiated in 318 matches (that we have data for) and there have been 8,580 appearances by players in those matches. Note that I’m saying appearances and not players because a player can make multiple appearances, i.e. play in different matches. 1,716 of those player appearances resulted in a yellow or red card, which makes the figure for Carballo around one in five.

This graph above looks at when referees first give out a card on average. As explained in the graph, there’s data of over 200 matches for each referee, so we looked at each match, noted when the first card was given and averaged those times. And voila, the Spanish referee is the earliest on average to give a card out, viz. the 27th minute.

Here, we’re looking at who converts yellow cards to reds the most. That is, once a referee has given a yellow in a match, how often doe he give a second yellow to the same player to send him off (so straight reds don’t come into the picture here).

Looking at the data, Carlos Carballo again comes first giving out second yellows in 69 out of 1,740 cases where he has already given a yellow card, or 4 out of every 100 player appearances.

Martin Atkinson, a 45-year-old referee from England is the most lenient when it comes to this, only issuing second yellows in 21 out of 1,214 cases, or 1.7 second yellows for every 100 yellow cards.

The chart above may look complicated, but it’s simple in concept really. It asks the question: Who has historically tended to give out multiple cards (red/yellow) in a match? We looked at the data for each referee and then checked how many of those cards were the the first to be issued in a match, how many of them were the second and so on. How many referees just keep going on booking everyone in sight?

Looking at the distribution, and to absolutely noone’s surprise, Carlos Carballo again comes out on top. Only 16.8% of all the cards he has given out over 12 years were first cards. Compare that to Svein Moen from Norway, for whom 33% of the 597 cards were the first card in a match.

In fact, if you look towards the bottom of the four charts, Moen is one name that keeps cropping up at the opposite end of the table from Carballo.

Moen, 37, only books someone in 1 out of every 10 player appearances, or at half the rate of Carballo. The Norwegian referee also makes his first booking on average in the 43rd minute, 16 minutes later than Carballo.

So, all things considered, Moen is pretty much the Christ to Carballo’s Antichrist!

If you want a walk through of all the code I used to get the data and analyse it, you can check my IPython notebook.

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