Even dedicated managers sometimes get tired of their team(s) and move on and try new approaches and options. Trying to get another failing league to try to make your league work doesn't sound like a good option to me, you need to work with the good products that your league already has and build on it. Quick fixes (like going public) seldom result in long term, committed managers. You will still strike out on some of the new managers, but if nobody plays, nobody wins.