I don't mean to pick apart your post but its the only way I can answer your question, or at least address em to some marginal degree.
This wasn't completely answered with the Panthers, but in his first year Teddy Bridgewater and Mike Davis both had career years, which indicate that its more likely then not.
Joe brady took over the Bills offense starting December in 2023 and the Bills won 4 straight because of their offense. This gave coaches 4 games worth of game film over the offseason to look back on. But Brady kept that offense not just performing well, but consistantly good.
Again, not a large sample size to say with confidence, but it lends to the leaning of a bit more likely then not and hints at the capability.
Brady certainly has a low floor. But he and Ben Johnson are the only two coaching candidates that I can see with a very high ceiling. All the other coaching candidates from McCarthy, Kafka, Glenn.... All low to average floors, but also all low to average ceilings. I just have zero interest in shooting for average.