Nate Silver is overrated. In 2012 he got lucky by having an accurate prediction of an election result driven by a major factor he had no knowlege of: the collapse of Romney’s GOTV system (Orca) on the morning of election day.
Unless, of course, he had advance knowlege that Orca would collapse, and Romney would fall short on his GOTV effort ...
Actually, I think Silver is VERY good. Back in 2008 he absolutely nailed the Democrat primaries and I believe he was very strong on the 2008 and 2012 general elections.
His politics lean left, but he seems to always follow the math when it comes to projections.