I actually think, despite Fred’s supposedly more conservative persona, that if he dropped out or didn’t get in the race, Rudy would be the big winner.
I’m inclined to think you’re right about that. Fred is the only candidate (precisely because he is at the moment a non-candidate) who has not been tested in the “catching fire” department.
All the others have and there are not exactly flames leaping into the air.
IOW, the other guys behind Rudy have been around the race and had failed to capture the support of those who now are gravitating toward Fred. If he drops out and never gets in, many will either go with the frontrunner (whoever that is) or walk anyway. But it won’t result in a big bump for anyone in the middle tier.