Nate Silver is a meta-gamer.

Nate Silver is a meta-gamer.

He's a D&D player trying to figure out what he needs to roll when the DM won't tell the party the AC of the monster they're fighting. So he asks the DM, "What kind of armor is the orc wearing?"  The answer is chainmail. So Nate notes that he needs to roll an 11 if there are no other factors. So his starting point is that he's got a 50% chance to hit the orc. But the chainmail could be magic, the orc could have a dex bonus, or the chainmail could be cursed. So he uses his formula to take into account those other factors. And he weighs those factors differently. When his analysis is done, he gives a 75% chance that an 11 or better will hit. Other die rolls have different odds of hitting. 

So I guess what I'm saying is that he's even nerdier than you thought.