You know how in sports there are times where someone other than the big teams get to the finals? Let's take last year's world series, which pitted two first time dancers to the World Series: San Francisco and Texas. The ratings for that series were among the lowest ever. So almost immediately what the sports heads say is: well, if you're a fan of that team then you aren't showing it because you aren't watching.
The reason the ratings are so low would be because the major markets of LA, NY, and Boston all have teams who didn't make it..so they stop watching. Seems kinda obvious, but then again I just thought of it and I also never hear anyone mention it so maybe it's not.