Its good to be that kind of fan for your team. The Superbowl gives you confidence in your team. But this league can humble you very fast. It ain't easy maintaining a top tier defense year after year. If you have a very good quarterback and good playcaller you can maintain a good offense year after year. Is Darnold considered very good? Is his playcaller good? The only dynasties I've seen in my time had great quarterbacks. Joe Montana. Tom Brady. Patrick Mahomes. I can't put Darnold anywhere near that category.
I couldn't care less where you personally would put Darnold.
But to answer the questions you asked....
"Is Darnold considered very good?"
Answer : After having back-to-back seasons of helping his team win 14 games, then yes. He is VERY good.
"Is his playcaller good?"
Answer : We'll see. But so long as Fleury uses the same type of offense that Darnold excels at, that's all that matters.
Oh and hopefully we won't see any stupid trick plays like Kubiak tried early in the season.