Selectors advise that if a withdrawal eventuates the selectors may seek a replacement player but if not then a promotion upwards may eventuate (therefore players on the cusp at the top of an eight may find themselves at the bottom of a higher tier eight). That would leave that lower tier eight short of a player and therefore a bye for each round. If that withdrawal & replacement happens, or withdrawal & no replacement happens, at a stage of difficulty in timing then the selectors may at their discretion use a wildcard for the final playing list to keep an eight intact.