The life of a rookie quarterback is hard. They are drafted to a team that is often times desperate for a fresh start.
You instantly become the face of the franchise. You sign a big contract and now you have to do something with all this money.
You move to a new city and try to get acclimated with life after college. Oh, and then there is the whole “competing on the field” part. It’s just hard, and more times than not rookie quarterbacks fall short of their expectations.