I see no reason Dak can't come out and play as well as Ben Roethlisberger did in his first year. No, Prescott wasn't a first rounder but he is coming off similar college success. There was a difference in the level of competition because Dak played against much better talent on a consistent basis.
What's similar is the supporting casts in the pros. Both Ben and Dak had/have offensive talent to help them transition into being a successful leader. Neither had to carry the load exclusively since they both weren't expected to start right away.
The Cowboys can win this year. Hopefully, we get through this year with a lot to look forward to next year.