Per Mertesacker in Kicker interview, talks about Wenger

On the criticism Wenger receives for not changing his ways:

I have witnessed it several times that there were questions about the manager in public. That is quite normal at a club that goes for the league title. But we responded well with some results. By doing so, not only the team but also the coach is in a much better position.

It is not like he sticks to his old methods. He changed some things by bringing in new players and by changing his behaviour. He changed his coaching staff, he acquired some fresh, young people. The video analysis has changed. In the summer, Shad Forsythe came in from the [Germany] national team as the new fitness coach.

Those are examples that prove that he is open to new things and that he takes advice. One of his strengths he has never lost in all those years: his charisma. He is the calm center of it all – that’s what he brings across.