Tuesday 4 June 2013

Where The Talent Shone Through In 2012/13.

The close season is always a busy time of the year even if very little action takes place on the field of play. Managerial change, although often planned months before can often drag on for longer than anticipated and transfer deals that seem certain to take place and enhance next years title challenge can also flounder as other sides take an interest.

The end of the season is also the perfect time to assemble team and individual statistics. Team makeup has remained relatively stable and the ageing patterns that can impact on individual players over multiple seasons are largely absent.

This post isn't going to be a data dump, in deference to the many sources which have sprung up to provide a multitude of different types of mainly Premiership data. Nor will it try to make concrete connections between the numbers and various significant match outcomes. Instead I will try to firstly look at how efficiently EPL teams carried out certain tasks during 2012/13. Variation in efficiency numbers will inevitably occur in the relatively short space of a single season, even where there is very little difference in talent between all the sides. Random variation ensures that everything we attempt to measure is a combination of skill and luck, with the former beginning to overwhelm the latter only in much larger datasets.

The wider the actually distribution in efficiency stats compared to that expected from the league average, then the more likely that there are factors involved in the execution of these stats that differ between teams. In short some, teams are more adept at carrying out these actions than others.

I'll then list how strongly these actions correlate to the broad measure of success enjoyed by each side last season. Correlation doesn't naturally lead to causation (leading may cause teams to carry out tasks more efficiently), but knowing there is a correlation is a good starting point for further investigation.

Accurate passes in the attacking half.

Arsenal top the efficiency stats with success rates of nearly 78%, closely followed by both Manchester clubs. Reading prop up the table with 58% and the range of conversion rates on an average of over 10,000 passes per side strongly indicates different levels of team ability in this area of the pitch. Correlation to success in the final league placings is also strong, although Wigan are a notable outlier with top five efficiency recorded from above average frequency of attempts. Similar results are seen for the final third of the pitch, but with even stronger end of season correlation. Wigan slip to near mid table, with below average frequency when we move further up the pitch.

Accurate passes in own half. 

Efficiency now ranges from 93% success rate for Manchester United to 84% for relegated Reading and the frequency of attempted passes for United is twice that of Reading. Again there is a likely significant difference in the ability of teams to carry out such passes and correlation to league position is also strong. Wigan are again the best of the relegated sides, but now reside in the bottom half of the ranking.

"We pass better than you do".
Accurate Long Balls.

Last of the stats where there is likely to be a very large, real difference in ability to carry out such on field actions. Given the lack of love for long balls, there is a surprisingly strong correlation between the ability to play them well and league success. The top four in efficiency are the two Manchester clubs, Arsenal and Liverpool, Tottenham and Chelsea are 7th and 8th respectively. Two of the bottom four were relegated, QPR and Reading. Completion rates range from 67% to 43%, but lower overall attempts averaging just below 2,000 for the season, mean a little more regression towards the mean is needed to improve the likely accuracy of these raw figures.

Unsuccessful touches of the ball.

Ball control matters, or perhaps a team which gets ahead can make easier passes and bump up their efficiency numbers. The Manchester clubs and Arsenal have the least unsuccessful proportion of touches, just over 1%, Stoke have the highest percentage of miss controls at nearly double that rate. Correlation with league position is again strong and once again Reading and QPR occupy places in the bottom four and Wigan found themselves relegated, despite another mid table berth.

Successful Aerial Duels.

Still a relatively high chance that one team can be significantly better or worse than another in winning balls in the air, although the correlation to league success is by far the weakest on show so far. Stoke are both the most efficient (59%) and the most frequent of aerial combatants. Reading contested almost as many high balls as the Potters, but succeeded in a league low of 42% and were relegated. Hoofing it, but to no effect and then in turn getting hoofed on? Ground hogging Arsenal contested 800 less aerial challenges than Stoke, but were third in league efficiency.

Changes of possession. Winning possession in the attacking third.

The top six are all in the top eight of teams ranked by their efficiency at winning possession in the final third and the three relegated sides are all in the bottom six. The elite also have frequency rates in excess of three times those at the bottom of the list. Possession alone tells you little, but where and how often you win it seems to add a much needed context to the beleaguered raw measure.

Accurate through balls.

There was a significant difference in the ability shown by teams when picking a through ball, but that talent differential didn't help them win or more accurately, it didn't correlate to winning in 2012/13. Wigan and Liverpool were among the most efficient and Manchester United and Stoke shared time with the worst, leading to a virtually zero correlation between league position and through ball efficiency. It was raw accurate through ball totals where the strongest correlation with league success was seen. Persistence, rather than efficiency appeared to yield rewards.

Percentage of chances created from set plays.

League leaders, Stoke created almost 20% of their chances from set plays, nearly twice the rate even the most set piece reliant of the top four teams, Manchester City. There was a reasonably strong correlation between set play chance percentage and success in the league. Unfortunately for Stoke it was a negative one. Team's which overly relied on set plays to create a goodly proportion of their chances were competing in a mini league where survival was the primary reward and 40 points the major aim. Cloth was being cut accordingly?

Percentage of chances that are clear cut chances.

What constitutes a clear cut chance will naturally be subjective, but in general more successful sides turn chances into gilt edged ones at higher rates than less successful teams. Manchester United were the kings of the tap in, followed by most of the rest of the top six. Norwich were notable interlopers and while numerically their total chances created were no real match for the title contenders, their efficiency certainly was. (although the advantage may be scouted out of them in subsequent campaigns). The relegated sides were among the bottom eight for efficiently turning chances into clear cut opportunities and that usual cluster of poor sides were joined by Gareth "shoot from distance" Bale's Spurs.

Successful set play crosses.

Another category where the spread in efficiency percentages implied that teams possessed different skill levels. The correlation with end of season success was reasonable and negative, the less efficiently a side found a teammate with a set play cross, the higher up the table they tended to finish. Of course deliberately over hitting a free kick doesn't automatically gain you more points. The likely causation is that players who are better in the air tend to be less adept in other areas of the game and success in these areas possibly lead to more wins for the majority of teams. Football, as Cloughie said, should be predominately played on the ground?

Goal scoring efficiency per shot.

We are now getting into more traditional territory and conversion rates with a regressed 13% for Manchester United at the peak and 7% QPR at the bottom strongly suggests a real talent gap from best to worst. This is reinforced by an efficiency ranking that virtually follows the final league table. Stoke fell to second last in a category that they excelled at in their formative Premiership years, as transition to a more pleasing style proved difficult and only a strong defensive showing, especially pre January kept them afloat.

Percentage of tackles won.

Category topping Manchester City won 78% of their tackles compared to a Premiership low of 74% for Newcastle. Not a huge discrepancy, but with average team tackle attempts topping 2,700 still sufficient evidence to assume that tackling talent does exist in differing degrees for EPL teams. A weak, positive correlation with end of season finishing position possibly indicates that England's premier league is still partly paying due respect to one of it's traditional strengths. Arsenal were the second most efficient tackling side last term, but the presence of relegated QPR and Wigan in the top seven weakened the correlation with finishing position.

Categories where 2012/13's numbers didn't really provide evidence for a real difference in talent levels, included the rate at which clear cut chances were converted (most teams can hit a barn door at ten yards with similar competency) and, to a lesser degree and in a similar vein, shooting accuracy.

The above list isn't exhaustive, but it is sorted in order of the probable biggest disparity in talent levels. It is certain that some teams were much more adept at passing the ball in the attacking half than others in 2012/13 and those more talented sides also tended to be more successful at the end of the season. Tackling ability was much less diverse, that's not to say tackling isn't a talent, but the levels of talent are likely to be broadly similar across the league from a team perspective.

The correlations are presented to describe the broad attributes shown by successful and less successful sides, at worst they provide a crude descriptive measure of the kind of actions successful and unsuccessful teams were efficiently or inefficiently engaged in during 2012/13.

Causation isn't assumed and neither is the direction and teams which perform efficiently, actions which negatively correlate to success may find those talents are essential to their continued survival in the EPL, but the majority of other sides choose to take a different course. Some teams chose to hone a niche approach, to satisfy their limited ambitions?

Equality of opportunity also isn't guaranteed, especially where individual events for each team fail to reach 4 figures, but the efficiency distributions spread around the league average can still be used to reasonably assume the scale of the different talent levels between sides.


  1. Interesting work!
    How come ball possession percentage was not taken into the analysis?

  2. I'm starting off looking at efficiency, rather than frequency although both obviously impact on final standings.