The scrimmages will tell us a lot about the quarterback room. I agree that part of the game is accuracy/arm talent, but people forget that the mental side of the game is where quarterbacks shine or fail.
If you can’t diagnose coverages and make split-second decisions on who to throw to, then you will fail. It doesn’t matter that you can throw laser beams all over the field.
That’s why scrimmage performance is so vital. The player who best grasps the game mentally will win, regardless of their arm talent.