His transformation since he's become more confident has been revealing in some ways. After all, he was hardly a young, insecure player when he arrived: he was accompanying his old coach, who had wanted him.
We've had several incoming defensive players go to pot almost immediately after arrival: Mangala is another who lost confidence massively within a few matches of arrival ( and I still thick there a lot of potential there). Nastasic took a bit longer but certainly had more potential than he was able to show here. Bravo's problems have been obvious, Javi Garcia took ages to show any quality (although perhaps he was one of the weakest players listed here); Fernando took age to perform to any sort of standard.
I don't believe that it's just because these players were shit. It makes me wonder whether there was something about or club - whether the personalities among the defensive players or the coaches - that made it harder for some of these players to settle.
I can think of far fewer attackers who took so long to adapt.