The Premier league has a new leader. On Saturday Arsenal ascended to the top of the table thanks to a misfiring Chelsea and a frozen pitch in Blackpool. Everyone knows about Arsenal’s fantastic attacking options providing the goals; Samir Nasri in particular is in the form of his life. But the most problematic, often criticised area is a defence which can give way too easily.

Image courtesy of Ronnie Macdonald. Under Creative Commons Licence.

On Sunday night, Robbie Savage was asked on Match of the Day 2 whether the Arsenal defence are the worst to top the league at this stage. Robbie’s answer was a definitive yes.

The question is – is this claim true? And whether it is or not – what is the relative state of the Arsenal backline compared to seasons past?

Our most direct answer comes from a simple comparison of the goals conceded after 16 games. Football wasn’t invented in 1992, but the Premier League provides a useful unit of comparison, so we’ve looked at the goals conceded in the first 16 games of each season since 1992-93 for the table toppers, and for Arsenal, whatever their position.

The data comes from the records up to 16 games into the season, solely for goals conceded, and there are some good patterns regarding a reduction in goals conceded by the top side after 16 games until 2004-05, and then a general increase.

Firstly – Robbie got it wrong. This Arsenal defence is not the worst to top the league. In both 1999-00 and 1998-99 Leeds United and Manchester United were top of the league at the same stage, both conceding slightly more per game than Arsenal this season. And in the inaugural season of 1992-93 Norwich City were topping the table with a massive goals against tally, eventually propelling them into European competition.

That first season is a bit of an anomaly, probably to do with the fact that Norwich were really overachieving at this point (see Transfer Price Index). Those first three seasons are also slightly different as between 1992 and 1995 the Premier League used a 42 game season, rather than 38 – but this doesn’t make a difference when comparing after 16 games.

One note about the statistics is that in 1999-00 Manchester United had a game in hand for one week, and topped the league on 16 games with 21 conceded, but Leeds’s data is included in this graph, as they topped the table first. In any case Manchester United have a game in hand currently, and had actually conceded even more than Leeds United that season overall.

The Arsenal Record

MOTD2 were getting at something though. If we look in more detail we can compare Arsenal’s record to that of the league toppers at 16 games, and Arsenal’s league position after 16 matches in the Premier League.

Arsenal’s current defence is certainly the worst for goals conceded at this stage in recent years by table toppers. Specifically since the rise of Chelsea under Roman Abramovich from 2003-04. The foundations for which were laid down by Claudio Ranieri, before Jose Mourinho took the reins and tightened the team further. In fact the only other year than this that a team has conceded more than 13 goals was the last time Arsenal were on top after 16 games in 2007-08 (though that season ended in a failed challenge).

However, technically for Arsenal the first 16 games of this season are an improvement over the same last season, purely on goals conceded. Arsenal have conceded 18 goals in 16 games, compared to last season’s 20. So this is actually a defensive improvement, not surprising given the clear out of the defensive line-up, removing deadwood such as Silvestre and moving on problems figures such as Gallas (although now performing well at Spurs). This could also be to do with a refinement of the 4-2-3-1 at Arsenal, as well as better cover from the fullbacks Clichy and Sagna, as well as the ever present Alex Song.

Arsenal’s league position clearly reflects the defensive record over the Premier League seasons. Their high positions (green line) after 16 games are consistent with goals conceded nearer to the table toppers. This shows you cannot be successful without a good defence or at least one as good as anyone else’s. This is clear at the moment, because this season all the top teams are conceding goals, and losing games on a level unheard of in recent years. Arsenal have lost two of their last six, Chelsea three.

The data threw up some other interesting facts when compared to the final standings. Here average goals conceded per game are used, to compensate for the fact that the first three seasons had 42 games.

No team has ever won the Premier League conceding over 1.18 goals/game. However the team leading the league after 16 games usually concedes slightly less per game, possibly because defences open up more as the season progresses.

The anomaly of Arsenal’s title challenge in 2007-08 sticks out, as they topped the table after 16 games – propelled by the midfield duo of Fabregas and Flamini, before the Eduardo leg break and Gallas break-down.

A team with a much stronger defence went on to win the league – Manchester United conceded an average of just 0.58 goals per game; the second lowest on record for the Premier League.

This data obviously only covers a small amount of league standings, and makes no mention of points gained, goal difference or goal scored, all of which are important factors in determining success. Last season Chelsea scored over 100 goals under Carlo Ancelotti, and that undoubtedly had a massive effect on their season.

Likewise Arsenal are well known for their attacking football under Wenger, and goals are what win games. But the aim here was to focus solely on goals conceded in light of the comments about the defence.

The Overview

Overall the picture is one of tight defences at the top of the Premier League since the arrival of mega spending in the top flight, and possibly the influence of more defensive tactics by managers such as Jose Mourinho. Arsenal play a much more open game, and the defence concedes more goals than would be expected for their league position today.

However, in the past there have been several teams with worse defences at the top of the league at this point, and teams with worse defences winning the league. In particular Manchester United’s win in 1999-00 came after conceding over a goal per game.

To mount a real title challenge Arsenal have to turn their defence into a unit. After several years of change at the back Wenger has finally got four quality centre backs, Vermaelen, Djourou, Koscielny and Squillaci, mostly with their best years of football ahead of them (possibly not Squillaci, the oldest). The problem lies in their recent arrival, and the lack of understanding shows at times, such as on Saturday against Fulham with Koscielny and Squillaci colliding over a header – leading to Kamara’s goal.

Losing Vermaelen (most starts last season) to injury was a massive blow, but Djourou looks like finally fulfilling his potential. Squillaci and Djourou need to gel and form a partnership to last through the current injury problems.

The other factor is creating a defensive balance in the formation. Arsenal play wonderful football, and they don’t need to stop, but tracking back after attacks and leaving the defence less exposed on the counter is key in shoring up the defensive leaks. Finally there’s the debate over keepers, but that’s another issue.

Wenger does not have the solid defensive record over previous seasons which some of his counterparts such as Mourinho or Ferguson enjoyed. The more recent data shows top defences conceding more goals and Arsenal don’t have the worst defence to top the league.

There are defensive issues to be solved if the team wants to win trophies, but the style of football does not preclude success – Arsenal can achieve their goals with their own brand – it just needs refining at the back.

More questions from our Football Data Blog: Is Wenger taking the Carling Cup more seriously?