Good player, but if we buy him, we're gonna need at least one more CM to be solid in that area. And if we somehow complete that daunting task, there's still the matter of our wings. Aside from Adnan, who's fresh and green still, we have no good wingers and you know damn well LvG's gonna wanna use those.
If we're buying him just because he's a good player and we have other midfielders near-done, then this is excellent news. But I dearly hope he's not LvG's idea of fixing our midfield up. He's good, he's also at a decent age and promising, but it's gonna take a lot more than him.
I sill think we should spend huge, around ~£50m for a world class midfield and buy players similar to Herrera, as in young and aspiring, but unproven, in other positions. Just my thoughts, though.