Russell Wilson and the Seahawks won when he was still in his rookie contract and they were paying out for their secondary and DL. Rodgers won in 2011 prior to his first big contract. Even teams that lost in the SB like the Rams also got there when Goff was in his rookie contract.
Mahomes is in the SB during his rookie contract right now. Foles was a backup and Wentz was in his rookie contract when they won. Eli Manning won in 2007, also during his rookie contract.
The bottom line is that if you can draft an elite QB and get him for 4-5 years on a rookie contract, that is your best shot at making the Super Bowl. The main exception to this rule is when you have an elite veteran QB accompanied with elite or very good coaching (Brady-Belichick, Brees-Payton in 2010, Roethlisberger-Tomlin in 2009).
Another factor could be if you have an elite or very good veteran QB and that QB is in the later stages of a contract when inflation of salaries renders his original contract less impactful.
The Broncos won with Manning and Kubiak, but they also hit big in the draft on defense with players like Von Miller. Then you also have the Ravens-49ers. In that case, the 49ers had Colin Kaepernick in his rookie contract, but the Ravens had Joe Flacco and John Harbaugh, if you want to call him elite.
Problem is, elite coaching is also hard to come by, and despite some positives, I'm not sure if I'd call McCarthy elite.
