I remember watching a young Jacques Villinueve in his Toyota Atlantic days. He was not even the best driver on his team, but it was him that landed the plumb ride in Indy Car, where he won the championship largely based on his consistency rather than race wins. Again, he was offered the plumb ride in F1 with Williams, where he managed to barely win the championship away from the much slower Ferrari.
Face it, driver skill has little to do with winning a championship sometimes. Each year there is only one or two cars that have a chance at winning any given event. Though he is talented, I cant help but think that Hamilton would be a mid pack driver with pretty much any other team, with the exception of ferrari.