They do not play them at their home ground. Home ground advantage matters because the microclimate/winds are different, the grass and bounce is different, the view of the goals is different, the shape of the ground is different, the 'atmosphere' is different. Its the same reason cricket teams do it tougher when overseas.
The requirement for travel is also signfiicant. I travel to Melbourne almost weekly, and I never don't notice the effects.
Ok, the Eagles beat Geelong twice but the MCG is not Geelong's home ground. Geelong's ground is an hour and a half and a world away. Plus, the Eagles of the early 90s were a significantly stronger team than all others because of draft concessions.
Brisbane did it for the same reason - big draft concessions. Ditto Sydney. Plus, they are both in the same time zone.
Adelaide did it, but they are a relative anomaly and alot closer to Melbourne than Perth teams.
Regardless, it is surprising this handicap has not been discussed in the light of the 12 goal turn-around in 3 weeks.
You can put Hawthorn's change in fortune down to a "bad day" in Perth, but surely the greater contributor is that teams generally underperform significantly when playing interstate.
So, how to redress this? It won't be redressed till the extra $10 million bucks hosting the match at the 'G is no longer signfiicant to the AFL. Perhaps the match can be auctioned off the the highest bidder, then W.A would be a chance to host a GF, particularly if Packer chips in (no pun intended) as well as some of those filthy richc Eagles supporters.
I guess it will make the Docker's eventual premiership all the more sweeter. Presuming of course we win one. My family planted a time capsule in 1999 and my submission was a single sentence: "I wonder if the Dockers will have won a premiership by the time you dig this up."