One of the smartest things that Arsène Wenger did when he arrived at Arsenal in 1996 to be met with a fair amount of scepticism among the players was to bide his time. He wanted to make sure that he took notice of how they operated before insisting that they take notice of his ideas. It quickly became apparent that of all the jobs on his list, a backline so well drilled they were almost telepathic was best left to its own devices.

Later on, the famous band of defensive brothers – Lee Dixon, Tony Adams, Steve Bould, Martin Keown and Nigel Winterburn – would all thank Wenger for the subtle changes that brought such rewards. They learned to look after their bodies, which prolonged their careers, yielded more medals and ensured they were still playing when footballers' salaries rocketed, so they got a slice of the action before retiring. He also encouraged them to express themselves more on the pitch. But when it came down to the nitty-gritty of coaching defence, it was clear from the off that they could teach him a thing or two, rather than the other way round.

Sixteen years on, Wenger is leaning on that expertise again. The presence of Bould, who was promoted to the role of assistant manager over the summer, has had a remarkable effect on Arsenal's approach to defending. That aspect of the game is hardly what they are famed for but Arsenal are the only team in all four divisions with a zero in their goals-against column. That is quite an improvement on this time last year, when Wojciech Szczesny had already fetched the ball from his net 10 times in the Premier League (albeit most of them came in a freak result at Old Trafford).

For a manager with the longevity of Wenger, it was noted, particularly in times of trouble, that unlike Sir Alex Ferguson he has always been reluctant to shake up his coaching staff. When Pat Rice, who had been his assistant from day one at Arsenal, stood down and Bould was appointed, the most fascinating question concerned the level of responsibility that would be passed on. Would a man who was part of Arsenal's most legendary rearguard be given the freedom to ring the changes? Wenger is notoriously controlling of the coaching regime and in pre-season Bould was given the green light to get to work with the defence.

Arsenal's captain, Thomas Vermaelen, has been impressed with the ideas that are being drummed in. "Steve is really good to work with, especially for defenders, as he has been a defender himself," he says. "He works a lot on the shape of the team and that is very important. He is very focused on details. To to be honest, I am learning a lot from him. I think having your shape right is one of the most important things in football, whether you have the ball or don't have the ball. We are working really hard on that and Steve does the job really well."

That emphasis on shape has made Arsenal much tighter as a unit so far. Bould's influence is reflected in increased levels of concentration not just at the back, but also in midfield – the area where players too frequently switched off and Arsenal were punished on the break last season. Kieran Gibbs explains that was high on the agenda. "I think most of the goals we conceded last year came from counterattacking," the left-back says. "That's the sort of thing we have been working on. We have been analysing and discussing that since the start of pre-season, and practising in training. Steve makes you want to play for him and everyone is really excited with the work we are doing in training, especially us defenders."

Wenger has been particularly pleased that two away games which usually pile pressure on the defence – at Stoke City and Liverpool – were examinations passed with calmness and authority. With Abou Diaby and Mikel Arteta operating from deeper positions to provide a steady base to midfield, and Lukas Podolski and Alex Oxlade-Chamberlain showing great willingness to track back where necessary, there is a much more solid feel about the team. That is even more impressive as Arsenal have had to play with second-choice players in two defensive areas – the inexperienced Vito Mannone deputising for Szczesny and Carl Jenkinson for Bacary Sagna. Szczesny is fit again for Southampton's visit on Saturday.

Bould could also make an interesting difference inside the dressing room, as a counterpoint to Wenger's preference for some quiet contemplation on match day. Bould was not a granite centre-half for nothing. He will not suffer fools and he will not be shy of a few choice words if necessary.

But there is much more to him than the stereotype of an old style, no-nonsense centre-half. During his apprenticeship as Arsenal's academy coach he developed teams with an emphasis on classy passing. It was a role he loved, describing it as "the best job in the world" as he nurtured players such as Szczesny, Gibbs, Jack Wilshere and Emmanuel Frimpong en route to the current first team. After 11 years helping to educate the club's kids, the offer to move up was, he says, "massively hard, but when an opportunity opens up like the one that has, I just couldn't turn it down".

On Tuesday night, Bould will undertake even more responsibility as he will be acting manager when Arsenal face Montpellier in the Champions League as Wenger serves the first game of a three-match European suspension.

In his playing days, when he won three league titles and two FA Cups with Arsenal, Bould worked under George Graham, a master at drilling a defence with such relentlessness they felt they could keep a tight line with their eyes closed. If he can instil some of that resolve now, Arsenal should improve considerably on the 49 Premier League goals conceded last season. Wenger is very satisfied with Bould's input so far. "He has taken over for the defensive job, where he is doing very well. Will we finish with the best defence in the league? I hope so."