This will be very short because I know nothing about football or the football equivalent of baseball's sabremetrics; but it seems to me that people have the same problem discussing Tim Tebow that Andrew Sullivan does talking about successful and wealthy people.
That is, many people say that Tebow is a great quarterback because his team is winning; and others say that he's a terrible quarterback whose team wins only through their hard work and luck. So which is it--personal success or teamwork and luck? Or a little of both? There are numbers involved, so can't we just crunch them and get beyond opinionated arguments that keep veering into political/religious issues? Get on it, Nate Silver!