I’m not sure they have done their research all that well.
I live in and my kids go to school in Floreat/Claremont, prime slime territory. In both my kids classes and their footy clubs, the Dockers supporters outnumber those from the other mob by a healthy margin. I’m no scientist and my evaluation processes aren’t endorsed by the CSIRO but even the supporter hats on heads count in Bold Park shows the West isn’t united. In fact, I would say it has a distinct purple haze.
The Eagles are to footy, what Clapham Rovers were to English soccer, some early success, like with the 1880 FA Cup but then fade into obscurity.