http://www.advancednflstats.com/2007/02/contact.html
Of particular interest:
Where did you get your data?
Most of my team data comes from open online sources such as espn.com, nfl.com, myway.com, and yahoo.com. It's easy for anyone to grab whatever they're interested in from those sites.
My play-by-play data comes from a source that's not publicly available, and at this time I regret that I cannot share it. However, I am working hard to develop a way to spread the wealth. One of my biggest goals is to help create a larger, more open, and more collaborative community for football research.
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There's no real terms of service so I'm curious as to the constraints in using this for commercial purposes. I most definitely want to use this for teaching purposes (how to text-mine, how to build a web app from data, etc) but want to know what terms the data can be redistributed.