I mean rookie deals have not existed for 2 decades. Was it 2011ish when that was brought in and Brady kind of skews the numbers. That is why I was looking at making a Super Bowl because at least then we have a broader scope.
If we want to look at the past 2 decades though we should look at how many teams the QB is a driving force on for teams in the Super Bowl which is less than I thought.
well since 2011ish if we include superbowl losers then it's 8 of 22 superbowl QBs (around 37%)
russell wilson x 2
patrick mahomes x 2
joe flacco
colin kaepernick
jared goff
joe burrow
let's broaden it even more though to conference championship games (you could reasonably expect those teams to be thought of as having been as worthy of a superbowl as the superbowl losers potentially):
2021: 3/4 were not on rookie deals
2020: 2/4 were not on rookie deals
2019: 3/4 were not on rookie deals
2018: 2/4 were not on rookie deals
2017: 3/4 were not on rookie deals
2016: 4/4 were not on rookie deals
2015: 4/4 were not on rookie deals
2014: 2/4 were not on rookie deals
2013: 2/4 were not on rookie deals
2012: 1/4 were not on rookie deals
2011: 3/4 were not on rookie deals
29/44 (65%) were not QBs on rookie deals - if rookie QBs were such an advantage, then more of them would go deep in the playoffs
and if paying your QB a shit ton of money was prohibitive of winning superbowls or just generally making deep runs then this would show itself in the numbers... if anything it shows the opposite
what it mostly shows is that good QBs get you deep into the playoffs whether you're paying them yet or not - in many of the rookie deal QBs who got to the conference championships's cases, they were later paid franchise money by their own teams
also worth noting that only 3 of the QBs on rookie deals who appeared that deep in the playoffs, only 3 got there before their 3rd year in the league (wilson, mahomes and kaepernick) which is also worth noting because in your hypothetical you make it seem like your rookie deal QB is going to step in right away and make you a superbowl contender as a rookie, when in all probability, even if they're great, they're not going to give you those sorts of returns until the final 2-3 years of their deal in the likely best case scenario if you're lucky