He did not necessarily have the fastest car at all, he put in the fastest lap. See this is where someone can take a fact and put a negative or a positive spin on it. It looks like most here are saying you are putting a negative spin on the facts Harry.
As I mentioned over on the other forum, Webber had to do a lot of his passes on the obviously dirty side of the track. Good tyres or not, to do that consistently takes exceptionally good driving skills because grip is going to be rubbish at that time no matter how good the tyres are. It seems fair to say that Webber, whatever his faults are, has a history of making good passes.