Derek Carr is still top ten in QBR this season per ESPN

3ParStillDriver said

There's a lot here. Its clearly a league problem. The offensive schemes have changed. Think back to the 2000's and 2010's.

Peyton Manning, Drew Brees, Tom Brady. QB's who stayed in the pocket and delivered passes with timing. Peyton Manning loved to audible to the curl route, and the ball would be thrown before his receiver even turned. We've seen back shoulder throws, everything across the middle and so on. It felt like QB's were timing throws to the route.

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The thing is that those guys earned the right to have offenses built around them. We saw that here when no QB could do what Brees did in our system. It's why Payton has changed his scheme in Denver.

College QBs aren't coming out from systems that do the stuff you are talking about. It's essentially all spread, RPO, and read option. So, NFL OCs are having to adjust schemes to do what those guys know how to do. If/when some of them progress to being like Brees, Brady, and Manning, maybe the offenses will be built around them and let them read and change plays. But, until then, things have to be simplified.

The result is that it takes guys like Darnold and Mayfield a long time to learn to play QB in the NFL. But, because of the cap and outside pressure, few teams have the luxury to let young QBs sit and learn like KC did with Mahomes and GB did with Love. It's a win now league because fan's won't even accept 3 years of mediocrity much less three bad years with a young QB.

Also, because of the portal and early draft entry, very few guys are getting 3 or 4 years of starting experience in college and as a result end up not being ready when they get to the NFL. But, it's hard to get those needed starts in when they get to the NFL if they struggle early on. Richardson is a good example of that.