We should bring back Marrone. Very composed and calm on the ball, excellent in defense, with room to improve. Better than wasting money on has-been (or never has been) players like this guy here. Sure, he's talented but is already 28 and wouldn't bring much to the team.
I don't even think we need a deep-lying playmaker of a DM in a formation with two CM's and an AM. It's just that Hernanes has failed so miserably in being a playmaker for us, that we've gone and tried to emulate Pirlo through Marchisio, Hernanes in a DM position and even Lemina, which obviously isn't going to happen as there's only one Pirlo. It's probable that the role will die with him retiring, as very few teams play with a diamond midfield nowadays. Everybody plays some kind of a 4-2-3-1 variation.