Sure, some of the bottom places shuffled around a bit in the intervening time, but if SSBM is anything like the other competitive games I play, that's probably only because the people making the list don't really have strong opinions about them. Every competitive player is going to pay attention to who's #1-5 in the metagame, but do you really think they devote as much attention to whether Bowser should be #25 or #26? They probably pick those on a whim based on whatever recent experience they had.
That explains the volatility at the bottom rankings. I don't think it's because the pros are plumbing the depths of the game to find new strategies to move a character from second-worst to third-worst.