I think the there is a little bit of randomness to this, insofar as Perth have been inconsistent since the break. When they fire on all cylinders in a game, no team can match them; their best will not just match but destroy any other team's best. However, that hasn't been showing up that predictably (we saw it in the Perth @ Melbourne and Adelaide @ Perth games).
So it may just come down to which games Perth explodes in. I won't say that top spot and HCA is sewn up, but minor premiers is looking more likely than not with the final fixtures. As a number of people have suggested, you just don't see Perth dropping a three-game series. (Of course, I didn't expect the back-to-back home losses either).