#2 Dean Ambrose must beat Seth Rollins
You don't have to look too far. There are just too many examples already on the roster. Bray Wyatt, Shinsuke Nakamura, and Samoa Joe to name a few are the wrestlers who were heels and had great momentum with them when they went into a match against a babyface.
But what happened when they lost? They lost all the momentum and the whole point of turning them heel went into the gutter.
Check out which wrestler EC3 finds cute RIGHT HERE
What is the point of turning into a Bad Guy if you can't win even by doing that? On the other hand, you had Daniel Bryan turn heel and win the title and has generated so much heat as a heel(precisely what he was expected to do).
It is at these crossroads that Dean Ambrose stands. If he doesn't win then all the momentum will go bust and what will be the point of turning heel if he doesn't even get to accomplish the task by doing that?