Its not about as much motivation, as its the solid Azzurri tactical system he plays in. Plays with a high quality unit and he only needs to do his role and not take much individual space, so he can be a decent player there. But when he has to step up on his own and prove himself in not as ideal sitaution like with Palermo where his sorry ass is supposes to be the star, he doesnt really carry them but instead mainly average.
Btw, stop comparing people to Stendardo, he is of no importance or any quality whatsoever (like doning on the Juve shirt 3-4 times makes him somewhat superior suddenly). He wasnt good enough for frigging Lazio's joke of a defence, Siviglia is their defensive star and he himself is crap. Imagine how the player he benches is like. Barzagli is not too great, but its an insult to say Stendardo is as good.