I think Val is a little more dangerous than you may understand. She went 3 rounds with Nunes before and Nunes is not a 5 round fighter, Valentina is a 5 round fighter. I believe that is going to be the difference.
I am also not sure that Nunes is as confident as you are about this fight. I think she knows she has to get it done in a couple rounds or it could be disaster.
For the record, I like Nunes, she is fun to watch. I am a Valentina fan being a Muay Thai fan and all and I just like her better so will be cheering for the bullet.