I think we've reached the point where Cam Newton can safely be called the best quarterback in the league. He has arguably the worst offensive weapons in the league, yet excelling and winning more than anybody.
He has vastly improved, but I can't call a guy who is 29th in the league in completion percentage, 27th in the league in passing yards per game, and 19th in passer rating as the best in the league. He also has a great defense. And I think teams like the Browns and Titans have much less offensive weapons around their QB's. But I do think he has vastly improved and has the slight lead in the MVP race this year.