When you have no QB in place and really no option to get one this year picking 15th unless they move up in the draft, the rebuild takes longer. QB is everything in the NFL. You can’t win in the league without one.
Lots of teams have won Super Bowls without a dynamic QB. Since TB joined the Pats, these are teams without a stud QB that have won the SB:
Season - Team (QB)
2000 - Baltimore (Trent Dilfer)
2001 - New England (Tom Brady - who at that point wasn't yet TOM BRADY, though obviously he would be soon)
2002 - Tampa Bay (Brad Johnson)
2007 - NY Giants (Eli Manning)
2011 - NY Giants (Eli Manning)
2013 - Baltimore (Joe Flacco)
2015 - Denver (Peyton Manning - who at that point was TERRIBLE...outright terrible - 59% passing, 9 td, 17 int, 67.9 rating, got benched during the season)
2017 - Philadelphia (Nick Foles)
So in the last 21 seasons, 8 of them were won by mediocre-to-bad QBs. Now on some of those teams, the QB got hot at the right time. And in some other cases, the team won primarily because of defense or a combo of defense and special teams. The QB wasn't the centerpiece of the team. That's nearly 40% of the time since TB entered the league, teams won with mediocre QBs (maybe you will argue that even in 2001, TB was elite, and though I don't think he was THEN, I won't argue with you about it).
There's more than one way to skin a cat. Having a great QB is just one way - and yes, it's *BETTER* to have a great QB than to not have a great QB, but you can win without one if your team is great in other ways.