Nate Silver of 538 Signs With Penguin In Two Book Deal
observer.com
observer.com
Go through that page with a basic statistical package, plus maybe Wikipedia for reference and you can probably see most of what he did.
See this earlier post:
http://news.ycombinator.com/item?id=356461
His baseball projections are based on a proprietary algorithm (PECOTA).
From wikipedia http://en.wikipedia.org/wiki/PECOTA :
detailed formulas are proprietary and have not been shared with the baseball research community.
I agree it's not super well-documented where you can just plug-in numbers and go, but it seems like he provides the details that someone else would need to do something similar.
It depends on your goal. If you want to exactly replicate his work, you'd need access to the exact same data, and maybe he hasn't specified exactly what he uses to train the regression model. But if you just want to do something similar, the ingredients are all right there.
Also, re: the "proprietary" formula, it means that you don't know the specific parameters his model uses. But if you just want to learn how to do something similar (which is what it seems like is your goal), the information is all there. The methods aren't proprietary at all.