Against Slavia Prague and Torino, we had Valero as the play-maker in the center of midfield. He was sitting quite deep and he was flanked by Brozovic to his left and Vecino on his right. Against Roma, Brozovic returned to his usual position in the center with Valero moving out left as one of the box-to-box midfielders. Seems a minor distinction to make but personally I was very surprised to see the lack of positional flexibility and the resulting impact on our game, so it's more important than you'd think.
Different games, different opponents and different tactics of course. But it just seemed to me like Brozovic was very isolated in the center when Valero moved up as one of the two-way CM's. However, Valero was nowhere near as isolated when it was his turn to sit in the center and play as our "metronomo".
I could be mistaken but I think I preferred what I saw from a "Brozovic - Valero - CM" setup, as opposed to "Valero - Brozovic - CM".
Brozovic can still contribute good amount of distribution playing as the LCM anyway, plus he's far more dynamic in that position than Valero. Valero is also the least mobile of our mids. Keeping him 'stationary' in a central position is probably safer than wasting his tiny gas tank running from box to box.
So for me it's gotta be LWB - Brozovic - Valero - Vecino - RWB.
Really hoping Lazaro starts because playing Biraghi and D'Ambrosio on the wings will be incredibly frustrating with their inability to attack.