We don't have a plethora of defensive central midfielders. I would keep him. Good option to have even if it is to bring on to protect a lead.
Would keep him as we are short in the centre of midfield - Granero is more attacking and M'Bia is surely being signed as a CB.
We only have 24 with numbers at the moment. That includes 4 keepers so I am sure one will come out - leaving 23 spaces - so 2 free. With Granero and M'Bia that takes us to 25. Only Young, Barton, Hulse, Campbell and Bothroyd remain without numbers.