I think that’s a harsh statement to make. Like
@bears51/40 said, rookies do shit the bed at times. I would except him to make mistakes but what makes the difference is if he learns from those mistakes or not. Is he gonna be a Trubisky who just never learned or a Mahomes who learned the more he played.
Let me define this for you, for the sake of being on the same page.
I think unless it is due to injury, the idea of ruining a GREAT quarterback is a myth. Having the mental toughness to be able to handle whatever comes their way is what makes them GREAT.
However, you can hurt a potentially GOOD quarterback. But not the great ones. And honestly, there have been plenty of times where fans have blamed a coach of an NFL team for "ruining" a player, when in fact, even under better circumstances, they may not have been great to begin with.
I've changed my mind on the idea of "ruining" a quarterback. I think if you can ruin him, then the peak of what you were going to get was Kirk Cousins level QB play anyway. But not a real franchise guy.
And for the record, that greatness in terms of mental toughness - I already see it in the kid Fields. I think he is going to be one of the great ones...