The manager told reporters: "He is more focused on defending well and helping out. That is what he has brought to the team and the squad.
"We had no real defensive midfielders. All our players in the middle of the park like to attack and are creatively focused.
"It is good that he is concerned by [defensive duties] because in our team most players are only concerned by how quickly we can go to the other goal. He has certainly contributed to improve our defensive record."
Arsenal face Manchester City in tomorrow's lunchtime kickoff.