The few minutes he's played this season, he's been mostly disasterous, sadly. As I wrote a while ago, he ended last season badly as well, and he's carried that horrible, error prone form into the the new season under Sarri.
His confidence is shot, and it shows, but I'm afraid his trouble lies deeper than that, which is odd considering how great he looked for the first half of last season. He's still young, though, with plenty room to improve, and his profile is perfect for us, seeing how composed he usually is in possession, has great passing abilities and can play both as DM and CB, meaning he could be a long term Busi or Piqué successor, but right now, considering how error prone he's been of late, I'm not sure he's the player we should bet on - especially not on the short term.