I'm going to disagree with your argument. How often does a average QB take a team to the Super Bowl and win? Out of the past twenty Super Bowls there have been five QB who you could consider average. Two out of those five won and that was because they had all-time Defenses. Your team pretty much already has to be built for a average QB to step in and lead them to a championship.
I understand not wanting to tank but situations like Delhomme are rare, so you're better off searching for a true franchise QB.