It has always been by conference.
I got demoted one season with a 9-7 record which would have had me finishing 3rd in the other conference. The 5th place team in that conference got to stay and I got demoted
I got demoted one season with a 9-7 record which would have had me finishing 3rd in the other conference. The 5th place team in that conference got to stay and I got demoted