Pjanic needs more freedom, it means that we need someone to take a big bulk of defensive functions, Lemina imo is able to do it. So far in this case we have Marhicsio as anchor, Lemina in front of him and Pjanic as mezzala somewhere near (I still believe it's his best position, because of the long and quick vertical passing he is very good at). To make this thing work we need quasi AM like that great drunken indio was (god we miss him, jigsaw will fall into place with him just perfect). For some reason I believe Benfica time Witsel is capable of doing it – he doesn't need to invent anything, play simple, win aerial battles and one-two with Pjanic-Dybala-Higuain. But whoever plays there needs good engine, not sure Witsel has it.