I will be the first to admit, that I'm no expert on Arbitron ratings, but I do have a couple of points about radio and in general and my listening habits.
First point is that the ratings are from 6:00AM to midnight, which obviously would include Sioux hockey. Next, when you get someone tuned into a station for a sports event you are more able to capture them for other programming. You build loyalty.
When I travel to New Orleans I listed to WWL. I started listening to them, as the home of the Saints. Now that is about the only station I listen to in New Orleans. A bonus is that they have such a strong signal I can get them in Pensacola.
We'll see how it shakes out in a couple of years.