So this assume there's no advantage to non-MCG tenant Vic teams hosting a non-Vic team in a GF?This was an interesting thought so I decided to figure it out.
Chance of tenant vs Chance of interstate Chance of Both MCG 28% 47% 13% Adelaide Oval 11% 94% 10%
So Adelaide Oval has a surprisingly similar chance of a tenant vs non-tenant Grand Final. There's a 2-in-18 chance that one of the Adelaide teams makes it, and if they do, it's almost certain (16/17) that their opponent will be from out of town.
But that's not all! HGA is different at different grounds, and tends to be higher at grounds that most teams don't play very often. So if you adjust for the fact that an Adelaide Oval GF would probably be asking teams to play at an unfamiliar ground, it works out almost exactly the same.
Chance of Mismatch Average HGA Points MCG 13% 8.5 1.11 Adelaide Oval 10% 10.5 1.10
In reality, of course, the advantage is worth 0 points most years and a bundle of points the other years. But on average, the disparity is worth 1.11 points per year at the MCG, and would be worth 1.10 points per year if the GF were at Adelaide Oval.
Riiiggghhhttt....
And as for this comment "if you adjust for the fact that an Adelaide Oval GF would probably be asking teams to play at an unfamiliar ground, it works out almost exactly the same.", you might be surprised as to how small the difference is between say Port Adelaide games at the MCG vs any Vic team games at Adelaide Oval, since 2015.