Firstly, to me, Romo was not a Jag by any means. He may not have won a championship, but neither did Marino. And Marino had an excellent coach in Don Shula. Besides 4 seasons with Parcells (only one of which had him starting), he had Jason Garrett as either OC or HC. Not exactly an awe-inspiring coach. And he got very unlucky in some games on teams that we were lucky to even get 8 wins in some seasons. 2013 was a season where Romo got so unlucky on several occasions. Especially in the case of the Broncos game, he had games where his play should have won us the game. But, our defence that year was so putrid that it wasn't enough. That season alone should teach fans that it's more than just the QB. You need an actual team around you. If Romo had a half-decent defence, we probably have a fairly deep run in the playoffs (before probably losing to Dan Quinn's Legion of Boom). Even then, we were one win away that year from winning the division. Mainly, because Romo led a fantastic comeback against Washington.....only to get hurt and miss the next game. 2014, he played brilliantly, but got very unlucky against the Packers. So, to me, he was an outstanding QB if not borderline elite. He just got very unlucky in some situations.
As for Dak, sure, he's not elite, but he'd definitely not a JAG. The numbers he's put up is very good. Yes, he had a bad season last season, but, overall, he's been solid. Mind you, he only had one noteworthy WR and an injured WR (along with a few tight ends) and Pollard to work with. I'm excited to see what we do this year with Lamb, Cooks, a healthy Gallup, and a nice trio at TE.