He was pretty good in the first two friendlies but awful in the one against Lyon. I honestly just don't think he has it in him to cover a regular-sized pitch, which of course makes him fairly useless as a box-to-box midfielder. If he's going to stay I think he'd be at his best as a backup defensive midfielder where he doesn't have to run as much and he won't make one side of the midfield devoid of creativity, he seems okay defensively as long as he isn't caught out of position like he is so often as a central midfielder and he'll only need to play a simple passing game which is the only thing he's capable of anyways. The depth might also be needed as De Jong is the only true defensive midfielder on the team with the departure of Essien and Muntari.
Either way when the time comes to trim the squad size there's a fair share of other players I'd get rid of before him, but he'll still have to impress in the coming friendlies if he is to stay. Despite his lack of ability there's never been anything wrong with his attitude, so we'll see.