Derek Carr practiced today.

What part do you disagree with? I think you like to argue for the sake of arguing. I do not really have any issue with this post with the exception of the fact that not every QB is a "systems" QB who needs just the right system and coaching. Most obviously, do.

My only point is that I do not think Carr would do much better even with quality coaching, playcalling, and a better system.
I'm disagreeing on the notion that Carr can't be coached to be an successful QB, as he was pretty good under Del Rio/Musgrave.

Also, if you look at the most successful QBs in the NFL, they are technically system QBs. We've done everything that we could to turn that into a bad phrase but the fact of the matter is. We've seen what happened when Brees left San Diego and came here to have a system built around and for him. We saw Peyton Manning bring his system to Denver. We saw Tom Brady struggling with Arians system and then turned about and implemented parts of what he ran into the New England system to the point where in 2021, Bruce Arians offense was pretty much pushed out the door. Every successful QB found themselves in the right system with good coaching. You would be hard pressed to find a QB that was able to find success with bad coaching and scheming.