I'd only disagree that Carr is an average qb. Last season was his first where he was decidedly average, and there were issues that led to that beyond him.
If he's in the right situation, I think he's solidly a top 10 qb. I see people saying he's not going to be any better because of our coaching, but clearly, if DA has another poor season, then next year, you get a new coaching staff and hopefully someone who can get the most out of Carr.
Whether he's worth it is certainly debatable, but considering how hard it is to find a top shelf qb, I think you get one while you can rather than waiting for a rookie to pan out.