I can't believe how quickly you lot turn on someone with obvious potential. You say he's going backwards, yet the facts are pretty clear to me.
When Mancini signed him, it's pretty obvious Mancini turned to him and just said 'You're my number 1 along with Vinnie, regardless of what happens, you will play if you're fit.' That automatically instills confidence in someone, especially at 19 years old, and it worked. Last season, he played without fear and with confidence, he made mistakes but he never lost his place.
This season, he got injured before the season had even started, comes back and Kompany gets injured and he just hasn't been able to cement his place in the team and that adds pressure. He's now going into games and thinking 'shit, if I fuck this up, I'm out of the team'. It's not Pellegrini's fault, far from it, but can you really hold all this against Nastastic? His manager last season had complete faith in him, this season, his new manager doesn't.