KR: Perth need 1 more win/or better percentage than 5th spot.
Perth have 5 home games remaining, that's a good start and a game winner in Cotton. Plus an inconsistent Adelaide in Perth. Which leads to the below:
Adelaide - fifth - requires +2 to get over Brisbane or Perth. With 8 games left, that's actually a pretty tough scenario. The run is tough - Melbourne twice, Sydney, Perth twice more - plus NZ away and Cairns away.
If Perth beats Adelaide in Perth, that creates another +2 hurtle for Adelaide to reach.
For Adelaide to make it, the requirement is a mixture of needing other teams to lose and winning not only any old games, but the right games, ie. beat Perth twice, beat NZ away, grab one against Melbourne and don't let Cairns get the better.
If the idea is Adelaide will make the finals, that means we're assuming the wins come from somewhere more than just Perth twice. Realistically, that might require beating Melbourne twice, or Melb and Sydney, in which case Melbourne's 7 losses doesn't look all that strong for a top 4 either, if you're allotting a loss or two to Adelaide.
Realistically, it's a bridge too far.
I think NZ are again, slightly lesser likely too - perhaps leaving their run a tad too late.