Great in theory...but you’re leaving out the most important part where you have to actually hit on the draft pick.
It's more complicated than the original poster is pretending.
You're right, you have to actually hit on the draft pick. But not just "hit on" the pick. It's not good enough to draft a regular old good QB. You could draft an all-time great, but if he doesn't win a ring in his first five years, his time with you is a bust because the original poster says you must reset with a new QB every time a QB finishes his 5th year.
It has to be someone special enough to win a Super Bowl out of the gates in his 1st five years (since your whole plan is to let him leave and start over after the 5th year). In the salary cap era, only 34% of the Super Bowls were won by a QB within the confines of 5 years from the date when he entered the league. That's 9 times in 26 Super Bowls during the salary cap era. And 3 of those 9 were Tom Brady, who was also the very first during the Salary Cap era to do it.
If the Colts followed this line of thinking, the Peyton Manning pick wouldn't have been a "hit" because his Super Bowl didn't happen in his 1st 5 years.
So you have to pick one of the rare special ones who wins it in his 1st 5 years.
But on top of that, it's more complicated because it also hinges on you using the money you saved wisely.
The minute you sign a stinker of a free agent deal that blows up in your face, it's all for nothing. You just pissed the savings and the theoretical advantage down the drain overpaying a position less important than QB being so great that it makes up for the fact that you rolled the dice and stopped re-signing good QBs you draft and develop.
Imagine you're a team who drafted a great young QB. He plays his five years for you and then you let him go. And to stack your non-QB roster with studs, you take the money you'd have spent on the QB and go give it to guys in the free agent market. But what if you pay a huge deal to a guy like Demarcus Lawrence and as soon as he signs his monster deal, he rewards you by regressing and only giving you 5 sacks? Imagine you sign Sammy Watkins, who you pay legit #1 WR money only to have him give you #2 or #3 WR production. Yikes. This is what you gave up your great young QB for? Oh boy. By choosing unwisely in free agency, you just misspent the money you saved by not retaining your QB, blowing the whole advantage this idea of a cheap QB was supposed to give you. Oh well, better luck with the next window in 4 or 5 years.
