Sunday, 20 May 2012

How Headed Goals Can Shape A Season.

After serving up 82 minutes of highly organised,if largely unappreciated defensive resilience to their German hosts,Chelsea fell behind to Muller's far post header from just inside the six yard box,courtesy of Kroos cross.The otherwise excellent Petr Cech was unable to lay a decisive glove on the ball as the centre forward's header flew first downward towards the turf and then upwards to nestle into the net via Cech's glove and the crossbar.

Five minutes later and The Blues were back level again following Drogba's thumping near post header from a similar distance.The effort being given welcome extra impetuous by Boateng's hefty shove into the back of Drogba just prior to the Chelsea striker making contact with ball .Neuer,like Cech previously managed to lay a hand on the ball,but it was already destined for the net.

Rewind nearly a week,91 minutes and 14 seconds into Manchester City's seemingly abortive attempt to land the Premiership title and Dzeko plants another decisive header into the net from inside the six yard box.As Silva's inswinging corner arched into the area it was clear that Dzeko was the clear favourite to make contact with the ball and although few would have anticipated the frenzied finish that would result,many fully expected City's replacement striker to bury that particular chance.

Headers,most especially those from close range appear to be extremely difficult for defences to deal with.Uwe Seeler excepted,most similar chances fall to players who are already facing the goal,there's no need to collect and control the ball and it is usually difficult for a defender to put in an effective challenge.From the keeper's perspective the ball is already well off the ground,he has little chance to "read" the strikers intentions and the ball can be struck downwards,as in the case of Dzeko and Muller or upwards as in the case of Drogba.

As goalscoring chances go,a header from close range would appear to be an almost cast iron opportunity to score,so using Opta data from EPLIndex and additional stats from the now defunct Guardian Chalkboards,I've tried to quantify headed goal attempts and illustrate their importance to certain teams.The data is naturally incomplete and almost certainly biased towards the teams I followed most closely via the chalkboards,but hopefully will be a starting point for more detailed analysis.For brevity,shots will refer to efforts made with the feet.

The most obvious benefit from directing an attempt at goal is either a score or the creation of a secondary chance from a forced save and rebound.So I initially used regression to estimate the likelihood that my basket of teams would see their effort hit the target.

How likely is a Shot or a Header to be On Target.

The usual caveats apply,sample sizes are patchy at some distances and the line of best fit is merely an extrapolation.However,at first shots appear to be a more productive option from all distances within the penalty area.Unsurprisingly,both headers and shots have a high probability of hitting the target when taken close to the goal line,but the accuracy of headed attempts falls away rapidly as we move outside the six yard box.Just over half the shooting attempts made from the edge of the box require a save or result in a goal,compared to below 20% for headers from such an "extreme" distance.

The anecdotal evidence at the start of the post suggests that in goal terms,headers are likely to be more to the fore from closer range.So now we'll look at how likely goals are from various attempts inside the box.

How Likely is a Shot or a Header to Result in A Goal.

Immediately we see the potency of close range headers.For the vast majority of the distance to the edge of the six yard box a header is more likely to result in a goal than is a shot from the same distance.If we return to the anecdotal evidence provided by the Manchester City QPR Championship decider,Dzeko's header left Kenny little time to react to the direction of the shot,whereas Aguero's winning shot from a similar distance a minute later at least afforded the QPR keeper the opportunity to anticipate where the strike was going and it also originated from the more conventional ground level.Saving close range shots appears to be a more equal duel between the skill of keeper and attacker compared to headers where the balance is more in the attacker's favour.

Only individually tailored team stats can identify teams which prioritize attacking this sweet spot in the penalty area,but EPLIndex do allow teams to be sorted according to the amount of goal attempts that originate either inside or outside the box.It's certainly a leap,but not an unreasonable one to assume that an increased proportion of shots from inside the box would also imply that the team also made proportionally more of their attempts from closer to the goal.Below is a table showing each team's cumulative shots,headers and goal attempts with various other body parts for the last four completed EPL seasons.

Which Teams Make A Higher Proportion of Their Goal Attempts from Inside The Penalty Area.
EPL 2008-2012.

Team. % of  Attempts from Inside the Penalty Area. % of All Attempts that Resulted in Goals.
Arsenal. 62.9 11.5
Stoke. 61.8 9.5
Aston Villa. 60.9 10.0
Wolves. 59.0 8.5
Blackburn. 58.3 9.3
Newcastle. 58.0 10.6
Manchester United. 57.7 12.0
Manchester City. 57.4 11.9
Everton. 56.0 9.9
Liverpool. 55.6 9.3
Bolton. 54.7 8.6
Norwich. 54.5 10.1
Swansea. 53.3 9.2
Chelsea. 53.2 10.0
WBA. 52.8 8.1
Fulham. 52.0 8.5
Sunderland. 51.2 9.0
Tottenham. 50.9 9.0
Wigan. 50.1 7.0
QPR. 45.2 7.8

The presence of Arsenal as the team making the biggest proportion of their goal attempts from inside the box won't surprise many.The image of Arsenal passing the ball and some would say the buck,before finally shooting has become an enduring emblem for both advocates and detractors of the style demanded of his charges by Wenger.Similarly the bombarding of the opposing penalty areas by Tony Pulis' Stoke is also a well worn cliche of their time in the Premiership.But no doubt fans of the respective teams will be aggrieved and amused that their heros achieve very similar attacking end products by employing polar opposite approaches.

Arsenal have probably achieved perennial Champions League participation by taking their scoring chances in an area where success is at it's highest,while Stoke have achieved survival relatively comfortably by shooting less,but also maximizing their production in this scoring sweet spot.As a consequence of their defensively orientated style,Stoke's attempts are always among the lowest in the league,but their conversion rate almost always exceeds that of their immediate competitors.

Indeed,whether by accident or design,The Potters also play in the most productive area of all,namely inside the six yards box and in the air.Below I've listed the number of goals they scored in and around the six yard box,in the most prolific area of the graph during their first two seasons back in the top flight.They were undoubtedly less skilled than virtually every other squad in the league at the time,so every chance made was precious and with a combination of Delap's throw,set pieces delivered with pace,tall players and an ability to make it difficult for keepers to command their box,they produced a rich harvest of goals,the majority of which came in front of a bemused keeper from the heads of Huth,Shawcross,Fuller and Sidibe.The data is taken from Stoke's yearly review DVDs.

Origins of Stoke's Goals,2008-2010.

Stoke's EPL Season. All Goals Scored from Inside Six Yard Box. Headers Scored from Inside Six Yard Box Total Goals.
2008/09. 20 14 38
2009/10. 18 10 34

The aim of good analysis is to discover areas of the field where you have the biggest advantage and then devise methods to deliver the ball into those areas,either via intricate patterns as in the recent case of Arsenal or more direct means such as Stoke's.Bolton under Allardyce famously deduced where the ball was most likely to be cleared to following a set play or corner and then always positioned a player there to pick up the second ball and judging by Saturday's UCL Final teams as diverse as Bayern Munich,Chelsea and Stoke know where to hit their lofted crosses to maximize their chances of netting.

1 comment:

  1. I like this analysis ...

    One of the things that irritated me about the Bayern/Chelsea game is the constant cutting inside from both Ribery and Robben ... this tactic of placing wingers on the opposite side with regards to their favoured foot has been prevalent in soccer the last few years, the Dutch use it extensively.

    This tactic cuts out the cross in for a header as the wingers don't make the back line and can't cross with their "bad" foot.
    It would thus seem that at whatever height the ball comes in from the side it is more dangerous than a player cutting in and firing from the corner of the penalty area.
    Maybe a tactic that teams who play like that should try exploiting again ... the constant movement that both Ribery and Robben made was very predictable and extremely easy to defend. It only works when they are excelling at the top of their game. Getting them to switch sides and throw it in to Gomez (or an onrushing midfielder) might have made for better opportunities to score.