Most of the history surrounding rookie QBs who start in Week 1 involves first round draft picks on bad teams. These QBs were brought in to save the franchise, and the team is in bad shape anyway, so they figure why not throw him into the fire?
Dak Prescott’s situation is a lot different. The Cowboys are a good team, and Dak is a 4th round draft pick. There was never any intention to start him Week 1 or at any point in year one, but due to Tony Romo’s injury and Dak’s great play in the preseason he’s received the opportunity.