I'm going to leave the homework with you to figure out why that is a ridiculous stat.
You are missing my whole point, which is to show that GWD is by itself a ridiculous stat.
Brady is the all time leader in GWD. But that's primarily because of his longevity. The calc I did normalizes GWDs over games played to derive the percentage of games played that were ended by a GWD. By that normalized stat Brady is 21st all time and Montana is 60th, so yes it doesn't work.
I wasn't p*ssing on Brady or Montana.
Count of GWD is what's ridiculous, as it is too heavily affected by longevity. Fixing the stat by normalizing it
shows that it is ridiculous. I did that normalization precisely to show that even game-normalized GWD's has weak correlation with excellence.
I of course am not proposing GWD/game as a useful stat itself.
To get what people think GWD is useful for you would have to normalize by using
opportunities as the denominator, not games. QB's on very strong teams (or very weak teams) get fewer opportunities to come from behind and win than QB's on mediocre teams.
My expectation is that Brady (and Montana) would score very high on a properly normalized career GWD/opportunity measure.
But that remains to be demonstrated so we don't actually have a measure of which QB's were best at winning close games.