1) I pay for some data (and it is expensive!) 2) I calculate/derive some data using existing data 3) Users have submitted some data to me directly 4) I've collected some data from open sources around the web
There aren't any/many open sports APIs because sports data is very expensive. I'm going to be launching my own sports data service in the coming weeks: http://embed.statsheet.com
Sometime ago (before I came across your network), I wanted to do a hobby website for cricket stats. I went hunting for the data, but all I could get was "records" data. I mailed a few cricket organizations asking for data, specifically mentioning that it was for a hobby site. They mailed back the pricing, it was prohibitively expensive, so I dropped the idea (it was for a hobby site anyway).
It would be great if your data service has an API and is affordable.
One suggestion. I don't remember seeing cricket in your network of sites, consider adding cricket. It has a hugggggggge base in Asia, Australia, and some countries in Europe (UK). Trust me, you'll gain millions of users overnight. You have to see to believe the amount of time people in the Indian subcontinent spend on cricket.