If he was that good Milan wouldn't have sold him and he wouldn't be in Brazil. Brazilians go back to Brazil to retire, he's just 24 which says a lot, why isn't he at another European club if he's that good?
Reyes was a flop, how many times has he been picked for Spain since 2006? None, not even as a squad player. He wasn't mismanaged he just didn't have it in him, that's why he's never been a start for any of the teams he's played for, he's not stood out for any of the teams he's been at since he's left Arsenal.
Vela is not bad, he's never coming back though and I'm not convinced he fits in at Arsenal.