It seems really obvious to me that the ranked system is flawed in the way that it is far to easy to drop a division compared to moving up a division. Currently, assuming you have already played the three "practice" games, if you are on 0 lp and lose a game, you will fall to the lower division with 50 lp.
To get back into the division from which one fell, not only must 50 lp be gained, but also the player must go through an advancement series containing yet another 3 games. It just seems like so much effort just for a player perhaps going on a small losing streak (keeping in mind I have currently experienced losses of 20+lp for losing a game, so it is not hard to hit 0 lp).
I believe that a 3 game series should also be initiated if a player is in danger of falling, therefore making it more likely that if a player is to fall to a lower division, it is indeed because the player was not good enough for his/her previous division.