If we consider than our starting midfield is Pjanic - Marchisio - Khedira, Pjanic playing as the attacking oriented midfielder, Marchisio the deep lying one and Khedira the box to box one, we need adequate replacements for Pjanic and Marchisio. Lemina and Sturaro are enough for covering the box to box role. However, we have none to be the Pjanic or the Marchisio rotation/backup.
I remember Asamoah being decent going forward. He was moving quite well and doing some nice 1-2s. I even remember a nice goal in CL after a combination with Tevez. Whatever he used to be, he isn't anymore though. The current Asamoah offers little to nothing. No creativity, no moves, not even stability. And yes, Witsel would be gold right now.
Also, we need a proper deep lying play-maker to be Marchisio's sub and maybe take over someday. Pjanic is totally wasted there. How's Tielemans doing these days?