Too many weekends against bottom teams. In the ECAC only the RPI/Union weekend is against bottom teams, otherwise you're playing at least 1 team in the top 10 in PWR and usually 2 in the top 15 or so every weekend.
I need to partially disagree with your interpretation. I am assuming we're just talking about the polls here -- the thread topic -- not pairwise calculations.
First, I'm sure we agree that the addition of St. Thomas to the WCHA means 4 more games against a "bottom team." Any new team is going to struggle in its first year. I still believe that Women's Hockey at St. Thomas is a very promising enterprise, and that we were correct to accept them into our league. But yes, for the short term, we have an expansion team in our ranks. That does provide an opportunity for the other teams to pad their records.
But to justify your sweeping interpretation, I believe you must also be targeting Minnesota State & Bemidji State. Browsing through the various resumes, it doesn't look good initially for the Mavericks and Beavers. Mediocre W-L Records, Goals against greatly exceeding Goals For. And yet I believe these "middle of the standings" WCHA teams would do just fine against the middle of the pack ECAC teams. This year that appears to mean Cornell, St. Lawrence & Princeton. I'm sure you recall that Bemidji had a win and a tie against Clarkson, who's running ahead those three schools. Note that Minnesota State routed Merrimack (WHEA) twice in road games, in their opportunity to play an Eastern team.
Next, I'm going to gently suggest that Dartmouth & Brown have pretty shaky resumes as well. Thus giving the ECAC contenders an opportunity to pad their records. No disrespect to those programs, of course. But the wins haven't been there in 2021-22.
OK, none of that proves "WCHA Superiority." But more to the point, there aren't nearly enough East/West games to justify a claim of superiority by either side.
As an actual voter, you obviously can and will vote on any basis you want. My position is that it's unreasonable for a poll voter to simply dismiss Minnesota State & Bemidji as "bottom teams." My eye test says otherwise.
(In the alternative, if you're exempting the Mavs and the Beavers from the bottom group, then one should compare St. Cloud/St. Thomas/Lindenwood to RPI/Union/Dartmouth/Brown. For a poll voter, I don't think it's self-evident that one group is stronger than the other.)