Schneiderlin deep with Herrera and Rooney either side looks like a decent midfield three to me - lots of work rate, decent physicality, and the ability to drive forward and bring the front 3 into the game. Reckon Mkhitaryan would like Herrera in that inside right channel too.
I'm obviously hoping we sign someone but we've got a good amount of CMs who offer a lot of different things, so at least Mourinho has something to work with in the current squad. Getting the midfield right is his most important job I think.
PS. I've got this Mkhitaryan spelling thing sussed, just got to think of punching Nazis.