It is obvious it is the latter - especially watching Jackson last year. If Jackson were here, he would be playing QB (stop with your WR histrionics lol). He has a stronger arm and is far more athletic than Mitch but he was raw coming in, no doubt. Harbaugh and Roman get all the credit in the world from me for developing him as well as the fact that he is elite talented.
When it comes to MItch, he has not turned the corner like Jackson has. I get you want to blame Nagy for it and I agree in part:
Nagy gets no pass from me; I dislike him and have no faith in him. But Mitch also gets no pass from me; I have seen him play terribly for long stretches of the season when WRs are open and protection holds up. It is not a binary position (Mitch OR Nagy) as you seem to imply; they are both incompetent as I have been saying all year.
Mitch would look better with a better coach but he still is not as accurate or aware as Watson, Mahomes, Jackson and I suspect any coach would take any of them before Mitch. Also, Nagy would look better with a QB that reads better and faster and is more accurate, yet still would be stupid for long stretches as well - ignoring the run game, kneeling on 3rd down when behind and being genuinely predictable especially during first halfs of games.
Together we have Mitch and Nagy (yeah us
Together they are 2nd to last worst offense and can only scrape up 17 PPG. Just a fact; and a recipe for a fall-off of epic proportions next year imo.