There absolutely shouldn't be a nerf when just switching sides of the same position.
Particularly given sometimes it seems like there's like 10 guys playing one side that you can recruit for every 1 on the other.
Personally, I think that the setback you have when switching positions in rating to begin with is already a disincentive to do it if you don't have to. So I'd be in favor of no nerfing for any position change...within reason. Like if you're switching a game from one linebacker slot to another, that shouldn't artificially introduce a cap.