I'm guessing for the most part they are going to keep whoever is currently in lead for their projections. It makes the whole projection process simpler.
Also, Utah is 8-4 at home in conference. They did lose one series to Oregon State but have some solid series wins in conference at home vs Cal and a sweep vs Arizona. I don't think it's out of the realm of possibility for them to win 2/3 at home vs the Beavers. I hardly think that's the most ridiculous assumption made in regional projections either