I think it's a mistake to put so much stock in QB Rating in earlier eras. Today when no one can play D, I think it's a lot more significant. However, it just amazes me that people will say "He had a better rate+" without looking at other factors which are directly linked to qb rating.
For instance, when you have a good running game and a strong defense you don't have to take as many risks as a QB. When you have a good D and are playing with the lead it's easy to throw the ball away or eat it on a sack when it's 3rd and 6 late in the 3rd quarter instead of forcing it into double coverage.
When you're down and your defense sucks..... you end up having to force things to make something happen because you simply cannot let the other team get the ball back. At that point, is taking a sack and punting the ball that much better than an interception? At least you're risking something good happening when you throw the football.
It's something that rarely gets talked about when it comes to Marino/Manning in relation to Montana/Brady.
I'm not saying that should convince everyone that they're better. Whatever. I'm just saying I tire of the fact that people never pay attention to this type of thing.