27 tds and 16 ints isn't all that different from what Carson was giving us in his good years. It's easy to focus on the terrible end to the season that our offense had, but overall I think Dalton had an impressive year. And more importantly, he improved from his rookie year to his 2nd year. Carson also had one of the best WR tandems in the NFL at the time.
My concern with Dalton is that even at best, falls into the Flacco zone of a guy just good enough to not "require" an upgrade, and not good enough to actually get to the Super Bowl.
How do we even know what his best is? And since you called it the Flacco zone, Dalton has had a much better first two years of his career than Flacco had, and Dalton was way more important to his team during those two years than Flacco was to the Ravens at the time.