Simply speaking, it means something is no longer in proportion i.e. or something could happen and now it's no longer in proportion (blow it out of proportion)
Example:
red = 5 apples
yellow = 5 apples
black = 5 apples
green = 5 apples
blue = 5 apples
....then something happened and blue received 10 more apples (this blew everything out of proportion)