Well I don't know.
What I do know is I played basketball all 4 years in High School, and if I went a week without shooting a ball, even a few days, I would be rusty. These guys have gone 4 months. Granted they may have thrown the ball around some in those 4 months, but they aren't just throwing a ball around anymore. They are throwing bullets, fades, leading receivers on routes, hitting them in stride, etc.
They are rusty. Give them time.
Why do you feel the need to condescend to strangers? I hate to tell you this, but playing an entirely different sport in high school does not give you any more insight into the QB situation than any other person.