Having faster time is good, but actually overtaking someone is something else. If Rosberg was ahead after the first lap, I'm sure he could've won it. The thing is you can pretty much do the lap you wanted in free air but following someone in current F1 can affect the car badly. And we aren't sure whether Rosberg and Hamilton fastest lap was set in a similar condition. Hamilton might get DRS advantage or use different engine mode or maybe Rosberg wasn't really trying. So I don't think you can use fastest lap as an indication that Rosberg couldn't won it if he was in front. What I can say is that I don't like Hamilton pushing Rosberg out of the track. If he can't manage to give Rosberg a car width, then he was going too fast. The way the track flowing, the guy in 2nd would get an advantage because he will get the inside line thus if he drove like nobody on the outside he could hit the apex better and carry more speed into the corner.