A phenomenal defense certainly helps. An average defense can certainly derail a team even with a HOF QB. An elite QB appears to allow for at least one SB win (AR, Roethlisburger, Brees, Wilson). In the last 20 years 25% of Super Bowl winners had average QB's from my previous post, 20% one-timer HOF'ers (above), 10% Eli Manning (possible HOF'er), 5% Mahomes (too early to categorize), 5% Peyton Manning in his prime, and the other 35% Brady. A HOF QB gives a team a shot but many more factors affect that also. We've seen ST blunders, coaching miscues and poor defenses kill GB's playoff runs in the past 20 years.