As a follow up, what I think would be interesting is this, specifically regarding Romo.
Games where we could have won and gone in: How many of those games were we actually the favored team?
Playoff games Romo was the losing QB in: Were we favored in those games?
I get your point, but I don't follow point spreads too much. I'm sure you could find them somewhere. I'm more interested in how the team actually performed, as opposed to how people thought they would perform. And you can look at things like defensive passer rating that filter out your QB's role.
The best way I can come up with to show that Tarkenton is HOF worthy:
Seasons Among Top 10 Passers
(adjusted for league size)
Peyton Manning (13) 1999-2010, 2012
Joe Montana (12) 1980-85, 87-90, 93-94
Fran Tarkenton (11) 1964, 67-70, 72-77
Dan Marino (11) 1983-87, 90-92, 94-96
Tom Brady (11) 2001-07, 09-12
Johnny Unitas (10) 1956-60, 63-67
Brett Favre (10) 1992, 94-97, 2001, 03, 04, 07, 09
Sammy Baugh (9) 1937, 40-45, 47, 49
Y.A. Tittle (8) 1948, 52-54, 57, 61-63
Len Dawson (8) 1962-68, 71
Ken Anderson (8) 1973-75, 77, 79, 81-83
Dan Fouts (8) 1978-85
Steve Young (8) 1991-98