Here's my theory: name the last elite read/pass option quarterback? Don't say Russell Wilson because he's not a read/pass option quarterback.
Furthermore, please name me the last elite running quarterback? Cam Newton, some would say. But Cam is not a great passer. His legs opened up the passing game for him, and now that he's beat up, teams don't respect his passing.
Dak's problem is the same as Tebow's problem is the same as many RPO quarterbacks on the pro level. If you don't develop throwing from the pocket skills EARLY in your football maturation, it is EXTREMELY difficult to learn them at the pro level because you have to unlearn all of the muscle memory processes you cultivated through a life time of football, and that's hard to do. There is an extent to which you can learn. And not facing pressure, it will make you appear to have "mastered" staying in the pocket. But let the bullets start to fly then human psychology takes over. And the human brain is wired to revert to muscle memory in times of pressure. You do what you've trained to do. And some of these guys have been trained to run when in trouble from Pee Wee football, Pop Warner football, high school football, college football, etc. Now, when they get to the NFL, quarterback trainers and offensive coordinators try to rework what they've learned all their lives, and it's very difficult to do.
So, Dak's problem is basically inherent to how he has played most of his life. And now the Cowboys want him to do something differently, and that on the highest level of football.
Again, I remain optimistic because I like Dak. But I have my doubts he will change. I was pulling for Tim Tebow - and very few had the work ethic and the strength of will Tebow did. But if even HE couldn't do it with the best of trainers, including the man considered a quarterback guru, I don't know if Dak can either.
We may be stuck with a more mobile version of Alex Smith or Kirk Cousins. Shrug.