His model is based on polls not his gut feeling and it has a proven track record.
Except when he gets it wrong, like Bernie winning Michigan.
"If Bernie Sanders were to defeat Hillary Clinton in Michigan’s Democratic primary, it would be “among the greatest polling errors in primary history,” our editor in chief, Nate Silver, wrote Tuesday evening when results started to come in. Sanders pulled it off, and now we’re left wondering how it happened. How did Sanders win by 1.5 percentage points when our polling average showed Clinton ahead by 21 points and our forecasts showed that Sanders had less than a 1 percent chance of winning?"