Statistical analysis of the correlation between ball possession and defensive organisation
When discussing the concept of possession football there will always be those for and against the ideals it propagates. How often do you hear generally uninformed 'pundits' use the phrase "I don't really like statistics, but…" before highlighting a side's possession figures to illustrate their apparent dominance of a game.
The nay-sayers to the importance of possession will preach it's not how long you have the ball, it's what you do with it that counts. That, of course, is as true as it is obvious but, in general, it has been found that in the majority of cases the team that has more possession will generally have more attempts at the opposition goal.
Indeed, possession always seems to be grouped with attacking intent, either when praising or criticising the premise. It strikes that far fewer of us consider possession as a defensive tool, despite the old adage spieled throughout football at any level that 'if you have the ball the other team can't hurt you.'
In theory that's another truth of the game but are there instances of possession having little impact on how effective a team is at limiting chances from the opposition? We've pooled the data from each side in Europe's top 5 leagues this season to find out, drawing comparisons and highlighting differences between the divisions.
The main thing to point out at first, however, is that it is clear that there is some correlation between possession and the number of shots a team concedes. Outliers are not uncommon though, and it's these sides that will be discussing here.
As the above graph shows the polar opposites of the possession-based game in England are Crystal Palace (37.8%) - with the lowest average in all of Europe - and Manchester City (59.9%). The difference, though, in the number of shots that each side concedes is arguably not as significant as one might predict. Palace, with 13 per game, actually match the overall average of the 20 Premier League teams in terms of shots conceded, while three sides have conceded fewer than City.
The frequency with which the Eagles concede chances is indeed almost identical to that of Everton and Spurs despite the fact that their possession average is inferior by around 19 and 18 per cent respectively.
The two aforementioned Europa League competitors are among the worst in the league when it comes to conceding a high volume of shots despite generally controlling possession. They, however, are not as far from the trend line as the likes of Swansea and Sunderland - the latter having conceded the most shots in England's top-flight despite having averaged more possession (45.9%) than 5 rival teams.
The most impressive at the other end of the spectrum, falling furthest below the trend line, are Southampton. Ronald Koeman's side's defensive organisation must be lauded having conceded the fewest shots per game in the league despite placing less onus on possession than they were under Pochettino, with 51.9%.
This figure is of course above the average but far from enough to account for the fact that the Saints have conceded just 8.1 shots per game thus far - all of this indicating that they are the side with the best defensive shape when out of possession.
A look at the graph above immediately highlights a clear grouping of 14 sides (top left) that would not be considered as possession focused, while Bayern Munich are unsurprisingly way, way out in front in this regard. They are truly the freak side of the Bundesliga and have steamrolled the opposition once again.
Germany's top-flight chart has a number of similarities to the Premier League though, from the angle of the trend line to the number of outliers that suggest that possession - despite Bayern's supremacy - isn't everything.
Hertha Berlin are certainly the Crystal Palace of the league in this sense in that they have had the least possession (42.1%) on average but have, somewhat remarkably, only conceded more shots than four of their Bundesliga counterparts (13 per game is level with Palace).
The fact, then, that Hertha have conceded the second most goals, while lowly Dortmund have averaged the second highest possession share and third fewest shots per game reflects the unpredictable nature of the increasingly popular German league.
Perhaps the best indicator of the fact that possession is perhaps less important in the Bundesliga is the difference in position between three of the sides well placed to be competing for a Champions League berth.
Schalke, who sit just one point adrift of third place ahead of the league's restart, have conceded the most shots in the league despite a near-average amount of possession (49.6%), with Gladbach's figures very similar. Bayer Leverkusen, whose average possession is admittedly slightly higher (52%), have conceded almost half the number of shots per game (8.4 to Schalke's 16.3), suggesting that Roger Schmidt's men are substantially better at reorganising upon losing possession.
It may come as a surprise that the league that is undoubtedly closest to England's top-flight in terms of the importance of possession when it comes to restricting opponents shots at goal is Serie A. Indeed, when it comes to shots conceded the leagues’ averages are identical (13 per game), while the trend line is extremely similar in terms of the effect of possession on that figure.
This time it's Chievo (40.9%) and Rudi Garcia's Roma (61.3%) at either end of the possession scale though both, in general, place close to the norm for the league in terms of its impact on shots conceded.
Given the assumption that the sides to the bottom right of the chart are the most effective in terms of their control over possession and organisation at the back it's no shock to see league leaders Juventus here. Their efficiency in this regard has enabled them to gain a stranglehold on the division, while the (re)emerging force in Serie A this season is Lazio, gaining pace after a slow start.
It's true that the Romans have plenty of possession (53.2%) but, with just 9.4 shots conceded per game, their defensive shape when out of it leaves them well below the trend line.
If Juventus' appearance at the business end of the graph comes as little surprise, so too do the presence of Milan rivals AC Milan and Inter above the trend line. Both former European heavyweights, the two have endured troubling spells in recent years that have continued into this season. Inzaghi's men in particular are proving far too accommodating to opposition attacks, conceding 14.2 shots per game (significantly higher than the league average) despite holding 52% possession.
A look at the graph for La Liga shows a clear difference from the three discussed beforehand here. Firstly the average number of shots conceded per game has taken a significant drop to just 11.7 per game, suggesting a less open and expansive style despite possessing two of the sides (Real Madrid and Barcelona) most renowned for their ability to completely outgun their opposition. The trend between these shots conceded and possession is also loose in a number of cases.
The most alarming of these is undoubtedly Atletico Madrid. Diego Simeone's side bombarded their way to the title last season (along with a place in the Champions League final) and, in the process, perhaps dispelled the theory that possession is key to success more than any other team in recent history. Despite key personnel changes, their approach has understandably not wavered.
Atletico have only averaged 50.5% possession this season but have allowed a meagre and frankly outstanding 8.1 shots on their goal per game. These figures highlight the unbelievable organisation of the side and Simeone's men are the model example to suggest that glory is not unattainable for the underdog.
Atletico's position, however, is not the only anomaly on the chart for La Liga, with Eibar's story the other true fairytale in Spain's top-tier. The population of the city in the Basque Country would fit into Camp Nou three times over, yet newly-promoted Eibar are sitting pretty in 8th. To defy the odds you have to first defy the numbers and Gaizka Garitano's men are certainly doing that.
They've averaged the second least possession (42.1%) and conceded the most shots in the league, whilst also only averaging more efforts at goal themselves than two other sides. There standing is an instance that is hardest to justify in stats and perhaps suggests that their fairytale won't last forever, but who'd begrudge them a little luck?
The division with the least significant correlation between possession and shots conceded is Ligue 1, shown by the fact that the trend line above is far closer to horizontal than the others here. Of the 5 leagues, teams in France's top-flight concede the fewest shots per game on average (11.5), with the amount of possession a team has, in general, having the lowest impact.
Take holders PSG for example, who are streets ahead of the competition when it comes to possession (65.6%), have conceded a very similar number of shots per game (9.9) as Nantes (10.1), whose average possession is almost 20% less (45.8%). Michel Der Zakarian's side have a very effective structure when out of possession, which has led to them conceding the same number of goals as long-time league leaders Marseille (22).
Saint Etienne, whose league-best defensive record has seen them mount an unlikely title charge, are similarly effective when out of possession, conceding the fewest shots in Ligue 1 despite averaging a modest 51% share of the ball. Meanwhile, the only real outlier above the trend line in the French top-tier is Reims, who have averaged 50.6% possession in comparison - a marginal drop - but conceded a far loftier 13.4 shots per game.
In conclusion there is certainly not a strict correlation between possession and shots conceded in any of Europe's top 5 leagues. There is a strong enough trend to appease those that value holding onto the ball highly to suggest that it does have an impact on the amount of pressure that your goal is likely to come under but perhaps a higher number of instances exist to indicate that it's far from the be all and end all.
Each league have representatives that are setting up extremely well when out of possession and that the likes of Atletico, Southampton, Saint Etienne, Lazio and Leverkusen are chief amongst them suggests that defensive organisation is arguably the true key to upsetting the apple cart at the top of the table.