It doesn't always appear to be a definite - but it is normally 2 up & 2 down. Over the years I have noticed that teams don't always get relegated that finish in the bottom 2. Teams that appear (in hindsight) to be placed in the wrong divisions that have won by a country mile I have noticed are occasionally (and I assume with agreement by club & league) moved up a couple of divisions so they can play more competitive footy. At the end of the day, it is down to the age group secs & clubs.