The inevitable questions over who will now score the goals for Arsenal were particularly pertinent in the aftermath of a 0-0 draw with Sunderland which suggested they were already missing their Dutch talisman. 

Yet many observers seem to have missed a crucial part of the Arsenal equation. There are two ways to cope with the loss of van Persie. One is the heralded ‘buy a replacement’ option, and find 30 goals from a new striker. The other is to simply concede fewer goals. Ideally Arsenal will hope to do both, but it is significant that for a team with such a poor record at the back in recent years there is little clamour among fans or the press for Arsene Wenger to bring in another defender.

In fact it is hard to think of a time since the ‘Invincibles’ of  2004 that Arsenal’s defence has looked stronger. Wojciech Szczesny is a reassuring presence in goal, a huge improvement on the days of Manuel Almunia. Laurent Koscielny was Arsenal’s unsung hero last year – when all around him were either losing their heads or fleeing elsewhere, he was the reassuring presence at the back for Wenger who kept things together defensively. Thomas Vermaelen, when he returned from injury, added another presence whom Arsenal could rely on, whilst Bacary Sagna and Kieran Gibbs offer reliability defensively and a useful option going forward.

In fact, the only real concern regarding the back four is Vermaelen’s tendency to step out and follow opposition forwards, rather than keep in line with his fellow defenders, a habit which almost led to James McLean scoring for Sunderland on Saturday.

Of course it takes more than five players to defend, and this is where Alex Song comes into the equation. Song’s influence last season has been hailed by all those questioning Wenger’s judgment in offloading the Cameroon international. Yet his most telling contributions were going forward. Whilst eleven assists and some sublime skill cannot be ignored, Song was meant to be primarily a defensive midfielder. Yet his indiscipline in that position has been the main reason Arsenal have had such a poor defensive record in recent years.

Arsenal have also suffered from an incoherent pressing strategy; as Barcelona have shown a team playing a high line and fast short passing game need to press their opponents quickly and high up the pitch. This requires a discipline and hard working mentality that Arsenal have been found lacking.

The defeat to Birmingham in the Carling Cup final was the epitomy of all that had gone wrong with Arsenal. Two highly talented players, Szczesny and Koscielny, contrived to throw the game away with an error born out of bad decision making. And bad decision making is the inevitable consequence of inexperience. Added on top of all of that, a back four often ravaged by injury have rarely been helped by Song’s inability to stick to his position screening the area in front of them.

Yet last year, for all the difficulties they endured, it was notable that Arsenal’s defence had a much better record with Mikel Arteta than without him in the midfield. Arteta was not at Arsenal for the calamitous opening three games of the season, when they conceded 10 goals. He was absent for defeats to Swansea and Manchester United mid season, and also missed the last five games, when Arsenal conceded another eight. Five of the ten games Arsenal lost were in the ten games they were without Arteta. Arsenal won just one of those games. Arsenal conceded 0.92 goals with Arteta, and 2.3 without him.

Statistics are often derided but they are invaluable to properly understanding the game. The significance of Arteta is that unlike most Arsenal players in recent years, he is both a primarily attacking player who does not neglect his defensive duties and experienced. Often last season the Spaniard was effectively Arsenal’s main defensive midfielder, dropping back to cover the spaces exposed by Song’s rampages forward. Yet Arteta is not a defensive midfielder. If he can have that impact, imagine what a real defensive midfielder would do.

Whatever happens, Arsenal will at least be improved by Song’s departure for the sole reason that they will have a defensive midfielder who may not be quite as talented, but is certainly more disciplined. Yann M’Vila is being heavily linked with joining Arsenal this week, but even if he does not sign, Abou Diaby or Francis Coquelin are more reliable when it comes to sticking to that position between defence and midfield through which Arsenal are so often undone.

Arsenal conceded 49 goals last season. Based on the statistics that Arsenal concede an average of 0.92 goals with Arteta in the team, it is reasonable to predict that they would have let in only 34 with a real defensive midfielder playing in every match, just one more than Manchester United.

Now look at who Arsenal have signed this summer. Olivier Giroud, Lukasz Podolski, Santi Cazorla, and Nuri Sahin’s arrival is imminent. Attackers they may all be, but one characteristic they all share is that they track back and are team players. Podolski and Cazorla are also both experienced, while Sahin and Giroud are both title winners. Arsenal have often been let down in the past by inexperience and poor decision making, as well as attackers who neglect defensive duties. All of Wenger’s signings this summer seemed designed to eliminate that naivety by bringing in a know how missing from Arsenal in recent years.

It is unrealistic and improbable that either Podolski or Giroud will replace van Persie. To score 30 goals in a season is an exceptionally tough ask. But if Arsenal continue to show signs of improvement in defence, discipline and shape, helped by new assistant coach Steve Bould, and the new forwards can chip in with close to 20 goals each, a more realistic target than finding another player of van Persie’s quality, then there are more reasons to be positive than negative for the Gunners this season.