Knowledge of the MU doesn't change any aspect of the character, it just makes you more able to adjust and play against that character's strengths. That much being said, Chizuru is probably the most well rounded character in the game; objectively, that hasn't changed. I can see Tamaki being ranked higher because of numerous factors (assist synergy, strong mix-up, high damage, ignorant supers), but she still suffers some issues from being stubby.