Wenger on the official site talks about the influence Jens will bring:
“He has a demanding attitude and can give his desire to win to the players, to help them achieve their targets,” the manager told Arsenal Player. “That’s what you want from these players.
“He can also give good advice because he has gone through periods where it was not easy for him, where it wasn't all going well, and I believe his rigorous attitude to his career is similar to Per Mertesacker. It’s important that a team is surrounded by people like that.
“He enjoys being involved in training as well, and to experience the pleasure he had when he was giving his best for Arsenal Football Club again. He’s still highly motivated and that motivation never goes. When you want to do things well, I don’t think that ever changes.”