They explain how to contact them if you'd like to sell an app. The idea is that they do not want you earning money from their data without them getting a cut. Similar to how Apple does not allow you to use their distribution channel without taking a cut.
Apple's solution is much more clear, however. Before you ever develop an app, you know to expect a 70/30 cut. If ESPN provided those details upfront, I'd be much happier. As it stands, seems like quite a risk to take.