Life has matured Dak as a person, which I think is a large part of what makes him such a cool customer in the packet and such a great leader.
Dak played 4 years and took a ton of snaps in the crucible that is the SEC. His cool under pressure and his quick thinking were partially God given and partially forged in those white hot SEC fires. Looking down the Barrel at loaded defenses against Alabama, Auburn, LSU, Florida, etc. made him into what he is today.
On the field he has all the physical tools it takes to be great in the NFL and he is smart. He understands the game. Two quarters in one preseason game indicates nothing about Dak's future success playing regular season NFL football. But Dak Prescott is not Justin Vaughan or Steven McGee or Chad Hutchinson or any of the other guys the Cowboys have tried to turn into real NFL QB's. Unlike those guys Dak has everything it takes to be a great one, including one of the truly great ones to watch and learn from.
It is between his ears and in his chest that has always made Dak a really good football player. Physically, he's very good. He is mobile, can take a hit and has no fear of getting hit because he's so strong. But it is his football IQ and his natural charisma and moxie that separate him from other QB's.