Wednesday, 6 February 2013

The Cult Of Passing.

Law 10 of association football is quite straightforward and states that the winner of the match is the team scoring most goals. If both teams score an equal number of goals or no goals are scored, then the game is drawn. There is no mention of extra credit for prolonged bouts of possession or passing. Therefore, although both possession and passing are important descriptive aspects of the game, they are merely a means to an end and that end is scoring a goal.

It has been recognized that possession is much less important than what teams do with that possession. The game winner can easily lose the possession battle and often equality of possession is not reflected on a lopsided final scoreboard.

With the demise of possession, it would appear that passing has now replaced it as the desirable stat of choice.

Few would expect Barcelona to raid the Liberty Stadium in an attempt to prise Leon Britton away from Swansea as a natural replacement for Xavi, but as recently as last week Britton's passing percentage was again being used as evidence of his supremacy in this most unnatural of match ups. Britton does most of his admirable passing a good Dan Biggar conversion away from the goal and conversely, Xavi operates in a much more elevated pitch position. Yet still the comparison between the two persists. Without context, the comparisons are meaningless and with context, the differences between the two players become apparent.

Having confused a creative, central midfielder with one who merely plays the simple pass, often from no deeper than the middle third, passing is now also being further used to characterize whole teams. The best teams, in general tend to pass more often and with greater frequency and these two attributes are highly correlated. If we now plot either passing frequency or efficiency against a measure of success, such as points per game, the case for passing appears complete. The better you pass, the more points per game you win.

The circle is complete. Passing is an admired art form practiced by the elite, they reap the rewards of excelling at the skill, while poor passing sides languish in mid table or worse. The implication is clear, to improve sides must become better passers of the ball. However, as with the repeating Xavi verses Britton standoff, the team passing debate lacks all important context and also suffers in the case of some teams from a confusion of correlation verses causation.

In the previous post I introduced in running success rate, a shortcut to adding context to a single match result. It's an offshoot of season long success rate, where the percentage of wins and half draws replace the arbitrary system of three points for a win and one for a draw. A goalless game sees both teams stalemated for 90 minutes leading to a success rate of 0.5 each ((90/2)/90). In similar vein a team winning 2-1 after conceding early goal and then responding with two late goals would have in running success rates of near zero compared to near one for a side which had an identical 2-1 win, but lead from the first minute to the last.

In running success rate adds information in a single number about the time a team spent either trailing, winning or drawing in a single game and that helps to add context to the stats each team recorded over that game, including passing stats.

If we now plot in running success rates for individual games for each club, as a proxy for the differing game states and scorelines each team experienced against their passing efficiency above or below their normal average in those games, we can start to see how important passing is to each team's ultimate aim of winning league points.

As usual, Stoke are the poster child for atypical behaviour during their time in the EPL and once again they buck the Barcelona driven expectation that passing the ball well should bring expected rewards, because the reverse appears to be true for Stoke. The Potters passed the ball more efficiently in games where their in running success rate was at it's poorest. The expected good passing premium doesn't apply to Stoke and on this occasion it also doesn't apply to others as well. Teams who pass better than they usually do when they are more likely to be in losing positions, indicated by low in running success rates, included from 2011/12, Aston Villa, Sunderland, WBA, Fulham, Newcastle, two of the three relegated sides, QPR and....Swansea.

It's easy to weave a plausible, but at best only half true explanations for this reversal of Barca model, but the assumption that better passing always gets it's reward and the arrow of causation always goes from better passing towards better results would seem to be flawed.

Stoke absorb pressure, then try to get into scoring position with low expectation, long passes. If they get ahead they then try to hold that position by absorbing even more pressure and use long balls as an escape route. So in advantageous game positions their passing efficiency starts low and stays low. If they go behind, they aren't suited or particularly able to pass their way through a now more defensively set up opponent, who are also happy to allow Stoke time on the ball in non threatening areas. Consequently, Stoke see more of the ball than usual in the middle third when their in running success rate is poor, but they are able to rack up higher, but ineffectual passing efficiency rates because of this concession by their opponents. In short, game situation sometimes drives Stoke's passing stats, rather than vice versa.

The Barca passing model doesn't fit Stoke's approach to winning points and it doesn't fit the approach of other teams, including Swansea whose incessant passing would appear to be less effective at breaking down more defensively minded, first scoring opponents. A model relating passing to points is too simplistic to capture the diverse way in which teams attempt to get the best from their available talent. A diversity which Law 10 encourages by making goals the only reckoner.

1 comment:

  1. It would be interesting to investigate would be passing success in different zones. My gut feel tells me that Barca has a greater passing success rate in the final third compared to Swansea (or any other team). This might correlate better to the in running success rate. Let us know! Great work on the blog!