I say it's Dalton's job to lose... but it's really Fields job to win, or it should be.
While it is unlikely that Fields will I think grasp enough of what he needs to do on the offense, I do feel if both he and Dalton struggles, Dalton gets the job, because he will be more use to the speed of the NFL and they can dumb down the playbook while not having a QB adjust to the speed of the game in front of him on the fly. The pros of this, Fields gets more time to not only work with the offense, but more of the bench WR's in learning. It will give him a player he is more comfortable with, and teams have put that guy out there on the field. So if there are Ridley fans still out there, this maybe his best chance to stay on the team, unless Fields likes someone else better.