One of our Arsenal writers uses Opta Stats to find out what makes a solid Premier League defence?
Usually, when analysing defensive performances, one tends to look at tackles made, interceptions, success in aerial and ground duels, and other such statistics. Indeed, within the English game, tackling is placed on a pedestal by many. Players going in hard are seen as fighters giving their all for the shirt. The physicality of such an event on the pitch has an animal spirit to it that often rouses supporters and players alike. Most fans, when looking at a new defensive signing, would probably ask, “Can he tackle?”
Imagine my surprise then, when, while looking at the defensive statistics for all the Premier League teams, I found the numbers charted in the following figure.
The Blue line shows goals conceded by all the teams. It, obviously, starts at the lower end with City (19) and ends fairly high up with Bolton (54) and Blackburn (59). Now intuitively, one might think that a side that has a better defence might be more successful with their tackling or they might be making more interceptions.
Strangely, in an interesting way, we see that the tackle success percentage for all the sides is between 71 and 79. And that curve clearly does not follow the same path as the goals conceded one does. Similarly, the line depicting Interceptions/Game does not follow a path that would suggest a correlation between higher number of interceptions and a solid defence.
What does it mean? Is tackling an overrated skill? Is it pointless to compare tackling abilities? Surely there must be more to it. Disregarding the importance of tackling would be absurd. Imagine a striker running at the opposition goal with only the last defender to beat. If that defender fails to make a tackle the striker will have a gilt-edged chance to score. The importance of tackling stands out at such moments during the game.
But consider this. Arsenal have made 15 successful last man tackles. No other team has made half as many. The top three defences in the League – City, Liverpool, and United – haven’t made that number of successful last man tackles in total! Does that mean Arsenal have better defenders or a better defence than these sides? Anyone who has seen a few League games featuring these teams this season is likely to instantly laugh at such a suggestion.
Further thought suggests that this number most probably results from a weakness in Arsenal’s defence rather than a strength. The defenders are exposed more often and opponents are getting more chances to run at their goal. While the individuals at the back have done well to make a number of last gasp tackles, overall the defensive unit has been leaky and relatively easy to stretch. Such an opinion corresponds better with the observations that most people who watch the Gunners will have made.
On the basis of the statistics mentioned thus far and the related discussion, it seems safe to suggest – not conclude – that tackling is an integral part of the game but is not a differentiating variable. A good defence needs players who can tackle but excellent tackling abilities on their own do not make for a solid defence. With that thought in mind it is easier to accept the lack of correlation between goals conceded and tackling success. Most teams, at the Premier League level, have players who are good enough to win a fair number of tackles. They’re all in the same ball park.
Last November, Xabi Alonso made some interesting points on this topic while talking with Sid Lowe of The Guardian. He said,
I don’t think tackling is a quality. It is a recurso, something you have to resort to, not a characteristic of your game.
I can’t get into my head that football development would educate tackling as a quality, something to learn, to teach, a characteristic of your play. How can that be a way of seeing the game? I just don’t understand football in those terms. Tackling is a [last] resort, and you will need it, but it isn’t a quality to aspire to, a definition. It’s hard to change because it’s so rooted in the English football culture, but I don’t understand it.
That makes perfect sense, more so in the light of the tackling numbers. Not only are the success percentages comparable, most teams attempt a similar number of tackles and interceptions per game.
This brings us to the next question. What are the differentiating variables that separate the good defences from the average ones? Evidently, this isn’t an easy one to answer as football is such an intricately linked game. But let’s look at some other stats to see if we get any closer to answering it.
Towards the end of January this website carried a thought-provoking piece by Omar Chaudhari on Premier League passing trends. The following chart has been borrowed from that article and depicts the number of final third passes needed to score a goal against all the teams. It is over a month old so the numbers will not reflect the impact of the recent fixtures, some of which were high scoring, but the broader picture remains the same.
Even without going into too much detail, these numbers are fairly informative. The teams that have conceded fewer goals are generally near the top while those towards the bottom tend to be susceptible at the back. Intuitively , the relationship between a solid defence and a high number of passes per goal conceded seems reasonable. But that in itself doesn’t tell us what makes the defences resolute.
At this moment, let’s take another quick look at the first figure in this post. The Red line for Shots Allowed/Game is an interesting one. It starts off with the League’s lowest number, Man City’s 16.31, and end with the three teams at the end conceding over 26.5 shots per game.
This isn’t as unidirectional a curve as that for goals conceded which, naturally, keeps on increasing as it goes from the best to the worst defence but it does have some similarities. Teams that have conceded fewer goals have conceded fewer shots. While those at the other end have allowed more than 10 shots per game when compared to City.
There are many reason that affect the number of shots a team concedes. Possession is one of them. If a side dominates the ball and pushes opponents back into their own half it is less likely to be threatened at the back. Indeed, the couple of dips in the SA/G curve belong to Chelsea and Arsenal who have conceded the second and third lowest number of shots. At 16.46 and 16.77 shots per game these teams are just behind Man City and actually doing better than Liverpool (17.20) and United (21.23, an uncharacteristically high number).
So we can say shots conceded, per se, is not directly correlated with a solid defence but it does provide teams an opportunity to reduce the number of goals they’ve conceded.
Talking about shots conceded, let’s take a look at one more chart. The following figure provides a ratio of shots allowed inside the box to those from the outside.
The first ten teams in this graph follow a similar path at that of the goals conceded curve in the first figure. After that it’s messed up.
It’s important to note that City, Liverpool, and United have a ratio of less than one. This means they concede more shots from outside the box than they do from inside. It points towards an ability to remain organized that eventually forces opponents into hopeful pops from distance. Most observers would probably agree that it is tough to break these teams down when they sit back and absorb pressure.
In the latter half of that graph, Stoke are a team that also has a ratio below one, 0.94 to be precise. They haven’t done as well with goals conceded but it does make sense when you consider their tactics. Tony Pulis routinely sets his team up to defend deep and narrow. They force the opponents to play in front of them and make teams work hard for good chances. This season the approach hasn’t quite worked out for them, maybe due to the stress of midweek European games or for some other reasons, but it does explain their ratio.
Finally, let’s look at one more graph. This time it’s for Offsides provoked.
The shape of this curve does not bear much resemblance to the one for goals conceded either but it does provide some talking points.
For instance, the three best defences are also the three sides with the lowest number of Offsides provoked. I found that a bit surprising at first, especially when you consider the generally attacking nature of these teams. Indeed, City and United are also the top scorers in the League so shouldn’t they be playing higher up the pitch and catching opponents Offside more often when they try to counter-attack?
As expected, Arsenal have a high number for Offsides provoked, the second highest in fact. Bolton lead the way on this chart.
The top ten defences average 45.5 Offsides over the course of the season thus far whereas the bottom ten average 70.5. This is a substantial difference and suggests teams playing higher up the pitch concede more goals when their tactic is to use the offside trap rather than dropping back. Nevertheless, there isn’t a direct relationship between Offsides won and goals conceded. So what’s going on?
In order to get a clearer picture, it would be worthwhile looking at the above numbers from the point of view of certain teams and their playing styles.
Let’s start with League leaders Man City. This season Mancini’s side have dominated possession in many games and have not been shy of attacking in numbers. They’ve scored the most number of goals but conceded fewest shots and goals. This suggests that City have the ability to control the transitions in a way that benefits them. From the defence perspective, it means the Blues from Manchester have the ability to slow a team down when they lose the ball. This minimizes the counter-attacking threat and the quality of chances that the opponents can create. They rarely try to play the Offside trap but quickly drop deep into a cohesive defensive structure or win the ball back high up the pitch. When the opponents do get men forward, the League leaders are able to put bodies between the ball and goal and remain well-organized. This forces the other team into hopeful strikes rather than those from gilt-edged chances. Ultimately, it makes them look very composed and assured as a defensive unit. It’s hard to imagine how the other side is going to score.
Essentially, City have mastered the defensive principles like Pressure, Delay, Depth, Balance, Compactness, and Individual Judgment. You can read more about these principles here in an article that is specific to Arsenal’s defensive woes but should provide sufficient broadly applicable information.
Teams like United, Chelsea, and Liverpool, have shown a similar approach as City but with varying degree of success. They too look very solid at the back.
Arsenal, on the other hand, have a significantly different approach. They too push forward in attack, perhaps more often than any other side, but the Gunners don’t seem as assured when the ball is lost. As can be seen from the passes needed to score against Arsenal, they’re not a team that is comfortable when sitting back. Similarly, a high number of Offsides won also suggests Wenger’s team try to trap opponents when they’re looking to get in behind. But the important point here is that the Gunners give the other team many chances to get in behind the defence. The Offside trap works more often than it fails but most teams will fancy their chances of scoring when facing Arsenal. It also explains the high number of last man tackles that they have to make. Structurally Arsenal are weaker than the other top teams and, as discussed in the article linked above, they aren’t able to transfer the principles of defending into practice as often as Gooners would like.
Under former manager, AVB, Chelsea seemed to be in a similar boat but their Offside figure is not as high which suggests they do occasionally sit back to defend. Swansea, Fulham, and Newcastle are other teams that seem to show a combination of defending by possession while also having the ability to drop deep in an organized manner.
Then there are many teams in the League that primarily rely on creating a well-organized, diligent, and tenacious defensive unit. Sunderland are probably one of the best exponents of this style. Steve Bruce, and subsequently Martin O’Neill have created teams that are very hard to break down. They don’t push forward as often but rely more on counter-attacks. Even though they do rely on defending as their core strength, Sunderland provoke more Offsides than the top three defences. This could be because of their inability to control transitions as well as the big sides which means they are more exposed to counter-attacks when they do push forward. It would also explain their hesitancy in using a possession based style in the first place. So they have to use the Offside trap when they get into the opposing half in numbers, especially when they are chasing a game.
Everton, Stoke, and Aston Villa are some of the other teams that use such an approach. Again the amount of success they achieve depends on many other factors like midweek fixtures, form, injuries to key players, etc.
Finally, there are teams like Bolton, Blackburn, Wigan, Wolves, and others that are towards the bottom of the League table and have conceded a ton of goals. It’s hard to say what their tactics are because they don’t seem to be working very well. For instance, they might set out to defend deep but an early goal might force them to come out and leave them vulnerable on the break. When teams concede a lot of goals it’s safe to say their structural integrity is compromised easily and they can rarely retain their shape while attacking or defending. In such cases, opponents can create a number of clear-cut chances against them which ultimately reflects in a smaller number of final third passes needed to score a goal.
To summarize, it seems safe to say that a much vaunted trait like tackling isn’t the most important skill in defending. The basic purpose of a defence is fairly simple – to keep the ball out of the net by minimizing high quality chances. This is done by slowing the opponent down, or by pushing them into wide areas, or by forcing them into taking low-probability shots, and so on. A team’s organization and their ability to remain compact and layered at the back is vital to a strong defence. This comes more from their players’ ability to read the game and to take decisions based on that reading. Unfortunately, we do not have good statistics that cover the defensive movement of a team. For instance, we don’t see any stats that show how well a side retains the shape of its back line or how efficiently they manage to compress the space between the lines. We don’t see the number of runs that are tracked or how tightly the opposing attackers are being marked. Without such analysis it’s impossible to quantify any team’s defensive strengths.
Tackling, interceptions, and such other individual events are important but nowhere near sufficient to judge the defensive performance of any side. It’s important to acknowledge this in order to analyze different teams and individuals. A defender might make a number of successful tackles in a given team. That does not necessarily mean he will be successful in another team. For instance, A full-back playing in a defensive-minded side might do well when he constantly receives the support of a wide player. His tackling numbers might be high as he constantly covers only one side of the winger’s run while his teammate tracks the other side. But in a different team that plays with a greater emphasis on attack, this full-back might be exposed when he has to cover a great deal of space on his own. Suddenly his tackling numbers will not look that good. Such problems happen regularly and are often the cause behind failed transfers.
With these thoughts I would like to end by saying that the above discussion is only a broad look at the styles of various teams and certain key aspects of defending. It is far from comprehensive and is by no means the only explanation. If it’s given you some food for thought and a fresh perspective on the art of defending it would have served its purpose.