Even as a Dak supporter I will say this:
While the performance of other aspects of the team have not been acceptable in the playoffs, Dak Prescott has also been a part of this problem. Maybe this is not a slight against him, because even Troy Aikman looked bad when his receivers were screwing up, the timing based offense was off, etc..
Dak gives the Cowboys the best chance to win right now, but he has not shown he is the type of player that can elevate the rest of the team when it's bogging down. Instead of rising up, Dak plays down there with the rest of them.
I hate to say this but this is what he has to prove to everyone. When the Cowboys are good, Dak is good. When the Cowboys are bad, Dak is bad. We need to see a game or two in crunch time when the Cowboys are bad, Dak puts his "nice guy" persona away, and rises up and gives them a boot to the rearend. And plays better himself too.