Can't believe what im reading here. Valverde is at fault for a lot of things Coutinhos form isn't one of them.
If you keep playing a player who is not a winger on the wing, then it is Valverde's fault. Coutinho will not get faster, taller or stronger and most teams have worked out how to stop him on the wing. Coutinhos best position is Messi's position but more central.