Most pro QBs say differently. 12 inches is open.
And how many times a game are they asked to attempt that throw? And let's not pretend Cam can't hit a twelve inch window, because he certainly can. But you can't ask him to take that throw every single time he drops back. The vast majority of successful offenses give their quarterbacks safe, easy throws either through play action or short screens. We don't use our running backs for crap so we have no play action, and we don't have the receivers that can make a short pass offense worthwhile.
A well-designed offense allows the quarterback to already know who the open guy will be before the snap. We don't allow Cam to audible, and the routes take too long for him to read who the open guy is before the rush gets there. There is a decisive mismatch between the offensive talent and the scheme and it has destroyed our season and is crushing our young QB.