I appreciate your comments on the subject guys.
Maybe what I am proposing is not the best solution but I don't have any other at the moment.
Still, the problem remains... and some creative people will have to find a solution one day because BB is a social game... everything should be made to encourage competition and trash talking between players (and not only between players in the higher divisions.)
Sure there are players who just want to do their own little thing with their team and not interact with anybody (imo they would be better off with a single player management game but that's another story) but in general, people play these games in part for the sense of community. I'm sure that the majority of new users don't stay in the game season after season until they "Oh one day" get promoted to a higher division so they can finally trash talk with their division buddies.
I just think of another solution to prevent the flooding of lower divisions with inactive users. Maybe instead of jumping right into the action, new users should compete in a short tutorial season against 4 or 5 bot teams. The tutorial would guide the user a bit like the actual manager checklist does but with more "hand holding". For example, when you edit your lineup, there would be a text saying something like "This guy would make a good starter in the SF position. However, his stamina is low, you need to choose a good backup. Maybe that guy?". People not that interested in the game would leave before the end of the tutorial so it would mean less ghost teams in real divisions. I don't think that people really interested to learn the game would be so mad to wait 4-5 weeks to play "for real".
The objective would be to quickly eliminate the players who realize that this game is not for them the first time they login.