вторник, 22 июля 2014 г.

Does increased possession equate to a better chance of winning?

Does increased possession equate to a better chance of winning?

By Mark Taylor Jul 22, 2014

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Possession has become one of the most contentious of the newly available range of soccer statistics that are regularly quoted in live match analysis. It is generally assumed that enjoying more possession is a positive, but does this assumption hold water, and to what degree should bettors use possession stats in handicapping a team’s ability to win games?

Taking Possession of the facts

The success of sides that take a possession based approach – such as Barcelona at club level and Spain at international tournaments – coupled with the aesthetically pleasing brand of passing football practiced by these teams, has made domination of possession an aspiration for many teams.

In addition, Liverpool’s Brendan Rodgers’ often repeated quote that “if you can dominate the game with the ball, you have a 79% chance of winning” is also taken as an endorsement of possession based football.

The success enjoyed by a short passing, possession orientated approach is much more mixed than advocates of this approach imply

However, if we take a more measured view of recent competitions, the success enjoyed by a short passing, possession orientated approach is much more mixed than advocates of this approach imply.

Holders, Spain bowed out of the 2014 World Cup at the group stage, despite having over 60% of the possession in defeats to first the Netherlands and then Chile. Also their success at Euro 2012 owed much to a semi-final penalty shootout win against Portugal, a side that had enjoyed only a minority share of possession throughout the tournament.

Barcelona conquered Europe in 2008/09 and 2010/11 with tournament possession figures in the mid to high 60% and pass numbers averaging around 700 per game. But sandwiched in between were wins for Inter Milan, 45% overall possession in the competition, barely a third in the final and just 400 passes per game in 2009/10, followed by Chelsea’s 47% overall possession in 2011/12.

Bucking the Possession trends

Numerous high profile head to head meetings have fallen to the side that shuns possession, most notably Chelsea’s aggregate win over Barcelona in 2011/12 gained with just 20% of the ball and Real Madrid’s 5-0 aggregate trouncing of a Pep Guardiola led Bayern Munich at the UCL semi-final stage this year with less than 30% overall possession.

Each of these examples is cherry picked and small in sample size, but they do appear to contradict Rodgers’ precise assumption, and the assertion that all a side needs to do to stand an excellent chance to win a match is to keep the ball for longer than their opponents.

Possession as a composite of other key stats

The major flaw with raw possession as a useful indicator is that it is a secondary statistic that has been derived from a composite of many other primary stats that are much more fundamental to a team’s success.

Teams get possession by being good at making tackles or interceptions, they keep it by passing well and they use their possession to create chances. They score goals by converting these chances and they win games by scoring more goals that they allow.

So we have a chain with match result at one end time of possession at the other, but in between are statistics that are ability dependent – often score line dependent – which are better indicators of match success. Possession in itself is not a strong indication of how well a side has performed. Of more importance is what a side is able to achieve with the possession it has.

Highlighting shortcomings with Possession

Swansea, in their early Premier League seasons, typified the confusion that simple possession figures can cause. The Welsh side were unconvincingly compared to Barcelona, primarily because their possession figures rivalled those of the Catalan side.

However, whereas Barcelona possessed the ball high up the field in their opponents final third and combined quick, intricate passing sequences – known as tika-taka – to create chances for world class players, Swansea’s use of possession was much more conservative, rooted firmly in their own half of the pitch, often comprising square or backward passes and designed as a defensive tactic centred around ball retention to prevent the opposition from scoring.

In the same 2011/12 season that Swansea were using the third best possession statistic in the EPL to create 472 chances, Barcelona were topping La Liga’s possession charts and creating 626 opportunities. The four sides immediately surrounding Swansea in the EPL possession table used similar levels of ball retention to create an average of 681 chances over the season, almost 50% higher. At the end of the season, Swansea finished a worthy, but mediocre 11th.

Swansea’s choice of how to use possession in a defensive, rather than attacking fashion was a result of their limitations as a recently promoted team. They protected an game start point in much the same way as more talented teams sometimes use possession to protect a lead.

Stoke City had travelled a similar route in 2008/09, with an inverted approach, this time by conceding possession and relying on chance creation from set pieces and long throws to generate their goal scoring opportunities, whilst making scoring difficult for their opponents with a packed defensive third.

The Mourinho approach to Possession

More illustrious sides, notably those managed by Jose Mourinho, also appear willing to sacrifice the ball in return for defensive solidity and the chance of scoring from counter attacks or set plays, especially when faced with technically superior opponents.

A game is sometimes won by an opponent’s mistake. Errors, in Mourinho’s view are more likely to be made by the team in possession of the ball and he is therefore happy to give them the opportunity to present his teams with a gift and at the same time attempting to ensure that the game remains stalemated.

Mourinho’s Chelsea demonstrated this tactical aspect of possession when his side went to Anfield as underdogs in 2014, enjoyed just 27% of possession, but defeated Liverpool 2-0, with goals from a Gerrard mistake and a swift counter attack, effectively killing the Reds’ title ambitions.

Although happy to possess the ball and dictate the course of the game against inferior sides, Mourinho is prepared to be adaptable when faced with a sterner challenge. The likely possession statistics for the Liverpool-Chelsea meeting were virtually determined before a ball was kicked, and therefore, should have been anticipated by bettors.

Pragmatism the Pulis way

Playing without the ball can often produce unattractive football and negative media reaction, but in many cases sides revert to these tactics to give themselves the best chance of achieving a favourable result.

Stoke City under Tony Pulis were technically inferior to many of their Premier League opponents, so an overtly defensive stance, both at home and away, coupled with long balls into the opponents half followed by brief bouts of pressing, was a pragmatic approach to maximize their chance of gaining points. Virtually every one of their 56 victories achieved under Pulis came with less than 50% of the possession.

Possession is only of minor interest, the real value lies with which primary events took place during those bouts of possession or non- possession

Possession is only of minor interest, the real value lies with which primary events took place during those bouts of possession or non- possession. How many chances did a side create or concede and just as importantly, were the chances of high quality or not? Since these types of statistics can be easily gathered and their correlation to goals and ultimately match result is strong, the need to quote possession diminishes and the temptation to try to draw conclusions merely from possession should be avoided.

True measures of team ability

The true indication of a team’s ability is how efficiently they use their possession in creating chances and how well they can stifle their opponent’s use of the ball when they have it. A side may out possess a side and even create more chances, but those scoring opportunities may be of poorer quality, due to their poor shot location and potentially higher levels of defensive pressure – something discussed in more detail here.

Chances created on the counter attack are converted at significantly higher rates than similar open play shots

Chelsea’s counter attack goal at Anfield and Ronaldo’s strike on the break for Real Madrid in the UCL second leg in Munich, easily beat an exposed goalkeeper. These goals from high quality counter attacks aren’t typical of all such chances, but using shot location data, it appears that chances created on the counter attack are converted at significantly higher rates than similar open play shots, which often involve slowly crafted build ups and allow the defence to become organised.

Therefore, it is wiser to attempt to draw conclusions from fundamental statistics such as shots, placed in their proper context, rather than assuming that dominant possession automatically indicates a superior side and any loss was unfortunate.

Low possession teams often have alternative ways of scoring. For example, in La Liga, the home of possession football, lower possession teams tend to score proportionally more of their goals from set pieces and counter attacks than do sides that have followed the Barcelona model.

This year’s champions, Atletico Madrid, scored a third of their goals from set pieces and counters, whilst enjoying 49% possession. That figure fell to 45% in the UEFA Champions League, where over half of their goals were either from counter attacks or set pieces.  In the final they came within three minutes of defeating their cross city rivals, Real Madrid.

Possession figures tell you little of how effective a side may be, although possession based teams may also be good teams, creating an illusion of a general widespread correlation. It merely helps to inform you about how they tactically chose or were compelled to play the match.

Mark Taylor is a freelance soccer and NFL writer who, along with producing expert content for Pinnacle Sports, also runs his own soccer analytics blog, the Power of Goals.

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