I'm not saying you're wrong about the "less-than-great QB's" statement, but I can only see five years where a SB winning QB wasn't a top 7-9 or so QBs' in the league...
--Foles
--Dilfer
--Manning
--Brad Johnson
--Flacco
QB's like Stafford and RW may not be considered great, but they were top QB's in the league. I even think Eli Manning might be debatable as at least a top ten QB.
I wonder what QB's comprised your fourteen? That's all.
In addition to the ones you mentioned...
Early-career (before he turned 30) Brady, who was good but nowhere near great, accounts for three of them. The debate back then was about Peyton Manning's sport-changing on-the-field performance with bad teams vs. Brady's "game management" and titles on great teams. It wasn't until his age-30 season that Brady had a top-ten-level performance, and he went way beyond that and had the first of a run of seasons at the level of Peyton Manning's peak that would run through Brady's 30s and early and mid-40s. So I split Brady into two. Brady after 30 is obviously great. Look at the press coverage and the debates before his age-30 season, though, and you'll see arguments about "clutchness" and "game management," because those arguing for him couldn't make arguments based on QB measurables for putting him even close to Peyton Manning. And even Brady being on the losing side of the Super Bowl after the 2007 season after a season in which the Patriots offense had run roughshod over the entire league, and the one after the 2011 season, couldn't dispel the idea that he somehow had magic title-winning powers. What's stupid about that is that 2007 was the first year when there were genuinely good arguments based on actual on-the-field performance for putting Brady at the top of the league with Manning, and not resorting to lazy narratives made up by talking-head mediots.
Giving in-his-20s Brady credit for in-his-30s Brady's performance would be as wrong as giving 2015 Peyton Manning credit for 1999-2014 Peyton Manning's performance would be.
And that's my segue to another one who's on the list. 2015 Peyton Manning. 2015 Peyton Manning can't even be described as decent, let alone good. He was downright bad that season when he was on the field (nine starts, ten appearances, 59.8 completion percentage, nine TD passes and 17 interceptions), and the Broncos won despite his awful performance, not because he was helping the team win. I see that as compensation for all the years when the Colts were what my mom called "Peyton Manning and some guys" and Manning did otherworldly things on the field year-in and year-out, totally changing what could be expected of NFL quarterbacks, but still ended up with just one Super Bowl title from his 13 seasons with the Colts. But the point is that while Manning viewed for his whole career is obviously one of the greatest QBs ever to have played in the NFL, he was a bad QB in 2015.
I don't like even mentioning this one, but 2005 Rapelisberger was good, but not great.
Eli Manning was good but not great in 2011, and was... OK-ish I guess (far from great) in 2007. He accounts for two of the Super Bowls
Wilson in 2013 was a game manager on a team that had peak Marshawn Lynch and an all-time-great defense. It wasn't until the second half of the 2015 season that Wilson performed at a top-ten level.
And remember, I've just been talking about the guys who won Super Bowls. There were others who lost Super Bowls who also weren't playing at a great level. Those guys' teams made it to the big game without top-level QBs too.