Isn't he a #10 and why do we need a #10 having extended Mata's contract? We sold Fellaini, released Herrera, Matic is aging, Pogba might leave and we're after an AM? Our priority should be strenghtening the deeper midfield positions like DM and CM. I know Fernandes can play as a CM too but his best and natural position is definitely an AM. He looks a really good finisher with nice shooting ability. Buying and not playing him in his best position would be much like ourselves though.
Also I don't like the idea of a diamond or 4-1-2-1-2 or a wingerless formation. It was used last season as we didn't have a proper RW but I can't remember a team that played without wide players and was a great success in the Premier League. At the very least wingbacks are a must in PL. We should build for a 4-3-3 with flexibility to change to a 4-2-3-1 IMO.
So, a good no 10 with great stats from last two seasons but not the player we need. We need wide players/wingers + central/defensive midfielders.