Offensive wise he is one of the most effective fullbacks in the world, defensive wise however he is a big question mark atm.
Bright news is that i can definitely picture him improving defensively under Allegri, all he needs to do is keep a clear head, stay humble and by this time next summer we could be talking about probably one of the best RB's in the world, imo management woudn't have taken the gamble if they weren't absolutely convinced about this guy.