Kind of. That QB carried them to a Super Bowl already. Their issue is more that they couldn't sustain the initial success. But that's mostly an ownership issue and ownership is nearly as important as the right QB.
Regardless, you are right that it take more than the right QB, but it's a lot easier and faster once you have that QB and it's easier to sustain that success by keeping him long term. It can be done with a mi-tier QB, but you have to hit on a lot more players in the draft and mid-tier QBs tend to fall off quickly.