Its acutally pretty simple. If you are in your proper division, your winrate will be about 50%. If you now play with a team thats way worse, with players that would never see a competitive team if it wasnt for the objective, your winrate will be going way down.
So no matter if you relegate on purpose, or try to do it without "cheating", you will get relegated until you are in a division where you can complete the objective much easier.