Well, all I can say is that when the Brazilian players come to Europe all the major clubs can easely see them, so they will have more chances to be famous that the ones playing in Brazil. Of course this doesn't mean that they can or can't improve here, but you know, european football is diferent from the Brazilian, so there's always a possibility that they can change a bit the way they play

Well, I can say as being brasilian myself too, that generally players get WORSE when they leave Brasil (yes, with 's' and not 'z'!). They go mainly for the fame, as clubs are paying amost the same as Europe does (to the best players). And they get worse because football in Brasil is much more offensive than in any other country, and as european team managers require them to mark and defend, they loose their dribbling sense and, to make a little sense in english, get "less smart" (behavior too "driven", just like european players) compared to those who play here or even to himself, before going to Europe. So, the amount they get better in defending is to little compared to the amount they loose of their attacking skills.