I still think Lampard plays as a RM for us. If Pirlo joins, it would make sense to play a "flatter" 4-4-2 with Mix as an 8 and Pirlo as that deeper midfielder. Lampard wide right with Shelton wide left. May make the field unbalanced as your RB now has more defensive assignments but Brovsky stinks up the field anyway.
Why not mix on the right? He plays there from time to time with the USMNT and he has done pretty well. Lampard has played in the middle most of his career.