(Valpo2004, sorry for long response)
There are only two games that I did not include in the stats mentioned. That being the games Bledsoe got injured (game 2, 2001)(loss) and Brady (game 1, 2007)(win).
Regarding the resting their starters game, there are included but only a few. If my memory is correct from 2000-2017, the Pats have only rested their starters for most or part of the game in the following years: 2005 v. Mia (the game which BB pulled Brady late in the game to put in Cassell who blew the game so they could avoid Pitt in the first round), 2009 v. Hou, and 2014 v. Buf. All of where starts by Brady but ended in losses as the team was not going full force. So 3 losses on Brady resume, if we remove them Brady resume goes to 195-52 (0.789).
And agreed with you we can not hold the 2014 Buf game against Jimmy G. as the starters were not in the game, but that is not included under Jimmy G. as i included under TB as he started that game.
And lastly, as a caveat we can looked to the last two games in the 2015 season, both looses, when the Pats were trading keeping the players healthy in exchange for not going all out. Which would bring TB resume to 195-50 (0.796) in games fought in anger.
To the question of "back-up" QB I think the real question for me is not the label of "backup" but how good is that QB. If Aaron Rodgers is the "backup" in Indy and they go 12-4 without Luck, does that mean Luck talent is qualified cause the "backup" went 12-4? Or do we look to the backup as a QB and judge from his talent? Minn is the #2 seed with a back-up, last years Cowboys went 13-3 with a back-up
For the most part Pats back-ups have been solid QBs. Bledsoe was the starter for us and was in 2001/2, and overall is a 0.500 QB with and without NE, Matt Cassell started for other teams, had a 10-5 season with KC, and overall is 26-40 outside of NE, Jimmy has yet to lose a start, Jacoby B. did what he did in Indy this year. Brian Hoyer who has not started for the Pats is 16-21 and 16-15 outside of SF. So the Pats back-ups fare pretty well outside of NE. They are not Rodgers nor are they Painter.
Agreed, the Pats FO does do a good job with fielding a good team and agreed that a QB is just part of the overall machine. In the end for me, a QB can help sway the results of a handful of game throughout the year and may include playoff games. For me the difference between a great QB and average QB is a small handful of games in the regular season and one or two in the playoffs.