Thursday, 21 June 2012

Is Ronaldo's Euro 2012 Improvement Just Down to Confidence?

The explosion of interest and availability of both player and team statistics means that many football articles now lean heavily on numbers to either drive or validate their narrative.An invitation to read on such piece dropped into my Twitter feed a few days ago as Prozone teamed up with the BBC website to give an insight into the performance of Portugal's Ronaldo over the three group games at Euro 2012.

The article was brief and to the point.Ronaldo had apparently gained in confidence from the first group game,Portugal's 1-0 defeat at the hands of Germany and was now showing the kind of potency he had demonstrated with Real Madrid in their Championship winning season.The website then provided a raft of Prozone data that was designed to reinforce the point,most notably Ronaldo's shooting and scoring exploits in the final match against the Dutch and his increased time in possession from the German game,through the Danish game and onto the final Dutch game.

Superficially,the points were solid,if unsurprising and appeared to be backed up by legitimate use of statistics.

The BBC's site firstly states that Ronaldo's confidence has increased as the group has progressed,but they don't demonstrate how they are measuring "confidence" nor do they tell us what levels his confidence was at at the start of the tournament following his astonishingly impressive season with Real Madrid.Fairly high,I would suspect.Furthermore,they don't explain how,in their eyes,a poor performance against Germany and Denmark can lead to and increase in confidence against the Dutch.Maybe their choice of words was poor and they are merely pointing out that his level of performance has risen as the tournament has progressed.

But this generous interpretation of their article also has problems.Firstly,we are talking about just three games,so sample size issues exist.It's tempting to look at steadily increasing or decreasing player statistics over a short timespan and associate these movements with nebulous qualities such as increasing confidence.But the reality is usually much more mundane and random.Looked at over longer time scales,players or teams will produce similar levels of performances,but within these runs of matches particularly good or bad patches will occur and these are not automatically indicative of an immediate decline or improvement.

The tactical approach of a team's opponents will also play a large part in how isolated sequences of games are played out.The first group game of an international tournament is characteristically low scoring because teams are reluctant to risk defeat.Initial World Cup and Euro group games have nearer 2 goals per game,whereas final group matches are much more open and average nearer 3 goals per game.Therefore it's hardly surprising to see an attacker,such as Ronaldo struggle for goals and possession in a first group game against Germany,but prosper in a final group game against a Holland team who were required to win by at least two goals to stand any chance of progressing.In short the priorities of Ronaldo's first and last group opponents were almost polar opposites.

It's also tempting to compare Ronaldo's much more frequent appearances with his club side with his appearances at international level.Football is ultimately a team game and during his earlier career at Manchester United and latterly at Real Madrid,Ronaldo has played on sides who were almost always odds on to win their games.By contrast,Portugal,especially in the final stages of world or European competitions are unlikely to find themselves odds on to win a game in 90 minutes and could occasionally find themselves the outsider of the three possible outcomes.In the opening Portuguese game,the average weighted finishing position of the the teams for which the German players starred for last season was 3rd in a combination of the German and Spanish leagues.For the Portuguese team it was 5th in a combination of Portuguese and Russian leagues.So the German team was significantly superior to Ronaldo's Portugal and therefore to expect him to dominate the game in the manner of his club form was unrealistic at best.

More detailed raw data is great,but match situation,opponent strength,context and an awareness of the randomness of small sample size makes it even better.The BBC's blog let down the wider statistical blogging community with it's use of without context numbers to bulk out mere opinion.Lee Dixon alone deserves credit for briefly mentioning that the open Dutch approach may have contributed to Ronaldo's "improvement",but I'd expect nothing less from a former Stoke fullback.

Lee Dixon,an insightful pundit in the making.

The Ronaldo who lines up for Portugal in the quarter finals will be the same player who starred in La Liga and played out the group games and his performance will be related much more to the tactical approach of both sides,the fluctuating scoreline and the relative abilities of the teams than a journalistic opinion as to his level of confidence.

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