Diame and Dembele are both crap.
Whilst I agree whole heartedly that we need improvement in that area what we need is to buy a player that will take us up a level in that area not just sustain us at the level we are at. If that makes any sense!!
Diame is no better than Lucas nor Gerrard and Dembele is no better than Henderson, especially in midfield.
I do agree we need a physical and powerful midfielder though. But the players I have in mind are the likes of Gonalons, Both Benders Lars and Sven, Gustavo, Reges, Marchisio, Moutinho, Cabaye, Strootman. The best in the world are Pogba, Vidal, Martinez, Bastian.S, Ramires, Yaya Toure, Busquets. I.e. unattainable.
That first batch of players would only be available to us if we have CL football. I mean we are heavily linked with M'Vila and he had that class once before and whether he can reach those levels again are another matter and could be worth a punt at the right price. But we need to upgrade and for me the likes of Diame and Dembele are not upgrades but sideways moves at best.
I personally am interested in seeing the dynamic of Gerrard further back and Lucas and Henderson further forward as it allows us to press further forward. But the huge drawback is the lack of tactical discipline from Gerrard and I don't think he can do it by himself but with a partner. Rodgers though does see Gerrard playing that role more often.
I think we need to improve both full back positions in the summer though. Flanagan is currently our best full back and that is saying something but we need improvement in those areas as with good quality full backs it allows our pressing game to be more effective.