I'd like us to evaluate and buy a new central midfielder based primarily on their defensive qualities - how many tackles and interceptions they make - instead of their style of play or their offensive qualities. That in itself would be a big step in the right direction.
I really like Doucoure. He isn't a pure defensive midfielder like Perreira, but he is so switched on defensively and has really underrated passing. He can switch the play and play forward passes between the lines. He also moves the ball very quickly. If Wenger doesn't just want a holding midfielder and wants someone who can do both as well as carry the ball and win headers. I can't see a better option.