If you adjust for reliability, most might agree that the W05 would have had 17 out of 19 1-2s, and who knows what would've happened in Hungary had Hamilton qualified on pole...
But I do think that reliability is part of the equation. Adrian Newey alluded to the idea that the ideal car would win the race, and then break down just past the finish line - since not breaking down means they have overengineered something and that would cost performance. Obviously, he went to the extreme to make his point, but I think it does stand. I believe there is a correlation between the W05's extreme performance and also their unrealiability.