To add to my point about RSNs eyes being bigger than their stomach.
Consider the Extra Innings and MLB.tv offerings. The people that buy those packages... they want to watch baseball. Is there anybody that buys this package and then never watches a baseball game? (Maybe the super rich). But the models on this are more reflective than RSN and ESPN coverage.
If MLB gets 10 billion subscribers to Extra Innings and mlb.tv this year... then they stand a good bet that they'll get 10 billion subscribers again next year.
RSNs and ESPNs and all the other sports channels that get "included" in people's TV offerings - which probably has a lot of people that never watch those channels. If they see 10 billion subscribers this year... that doesn't necessarily mean they'll have 10 billion next year. We're already seeing that, people are cutting the cord and dropping sports because they don't care about them.
Instead of actually focusing on the number of people that watch their content... ESPN and the RSNs just looked at subscriber numbers... because it was larger and larger looks better in an accounting book.
You can also sorta, kinda do this with other content, like movies and TV shows. And this is why I suspect you'll see production companies, studios, and distribution networks focus more on streaming. Take CBS All Access for example - people aren't subscribing to CBS All Access if they don't want to watch the content that is available on that platform. That 1 subscriber to CBS All Access means more than the 1 subscriber on DirecTV that has CBS and may never watch it.