you can tell the ability of the mercedes car quite easily that its about 4th best, by looking at qualifying laptimes, and especially sector times. rosberg managed to quite often get 7th which is the best after the top 3 cars.
maybe schumacher is driving as good as ever just that rosberg is more talented now? thats another view that some might conclude, we will never know, but schumacher is far less consistent then before.
if you look at qualifying sectors where every one is on the same fuel and putting in the same effort consistently puts mercedes 4th or 5th, in the same way redbull were consistently 1st, and sometimes second. schumacher too often underperformed in qualifying relative to his teammate, and thats a good indicator most times in f1 who is performing better.
i hope mercedes wont make the same mistake next season as this, building a car around schumacher (i dont know if that is actually true or not, but it seemed the case at the start of the season). build it around rosberg this time and see if they can get towards the front of the grid.