I notice him. He is too often out of position, or out of tempo.
He is not technically great either, struggled to handle a perfect, hard pass from Busquets today, for example.
He likes to have the ball, but often doesn't know what to do with it, comes deep to get it, looks up, finds no-one, passes it back 5 seconds later. Makes some forward runs, but they are often not so well synced.
He distributes the ball without real intention, he sees Dembele free and gets it there, even if the play should better move to the left flank. I think this has both to do with lack of confidence, but also lack of quality, unfortunately. Also a lack of direction from Koeman.
I am all the more confident he should be played as a CB. I had hopes on Koeman using him in his own old role, but he could work as one of two as well, with some work and with the right team mates.
He wants the ball in these spaces anyway, as a midfielder. He is very calm on the ball, press resistant, good on bringing the ball forward, can find a pass.
He is also decently fast, and should be able to compete for the ball with fast attackers better than Lenglet or Pique.