Some people just don't have the heart. And nobody will ever be able to measure that
If Rosen is struggling getting players into the right spot, reading a defense pre-snap or learning A playbook he's done
If you show those three things and show up every day early and bust your ass, you will stick longer in the league than you realize
Because a lot of players actually struggle with those three things. Look at a guy like Chase Daniels, epitome of a professional backup quarterback
He could do all those things with his eyes closed and he's got over a decade in the league, with like only a handful of starts
Rosen was supposed to be a pretty smart quarterback so if he can't do that he's toast