I have no idea why people are saying things like "Oh we've already got Sahin, so we don't need M'vila", they are 2 different players, and with Nuri our midfield is lacking severely in an experienced player who can reliably win the ball back.
In any case, I've grown cold on Yann. He's another young prospect who might very well up and leave when he comes good. I think any signing we make has to be viewed in the short term, or at least a solid EPL player who probably isn't attracted by Barca/Madrid. I think we may need more industry and physicality from our defensive signing as well. I'm not sure M'vila is quite strong enough to bully opposition midfielders. I don't think he is.