Meh, cars are slightly different these days, different balance and different feel. With very little testing available Rosberg and other drivers have basically 3 years lead on getting the right feel.
As simple as on this car, Rosberg might feel something in practice and decide the left front tyre needs more pressure and the rear wing needs less down force by a smidge, the problem is, now much in each situation, I would imagine it will take Schumi a while to get those slight changes down to an exact science for him and how he drives the car.
Judging by how Button and Hamilton throw their cars around, you'd imagine their setups are quite different so its not like they could just take Rosbergs adjustments and stick them on Schumi's car and get the right feel for his type of driving.
Personally I think Hamilton has shown time and time again he's easily faster at pushing the car around the track, and only in the last race did his tyres seem to give up early, and it was just one tyre, the other 3 gave up the same time as Button's and he was again faster. Yet Button's winning and avoiding trouble, different driving styles, different setups.
I think he'll get better, but if he has the will to really push himself to the edge, we can't know yet. He could be right on the limit but the car isn't letting him get further for now, or the car is fine and in a year he'll realise he just can't be bothered. Far to early to tell.
To a certain degree, just like Hamilton he's run into trouble in most races while Ros/Button haven't and have in many situations lucked out in the situation.
