[petraeus]

Can anyone explain how 538 got the last election so wrong?

Its quite obvious in hindsight their model is flawed, but Im not understanding how is it flawed.

[fourmajor]

If you're referring to either the midterms or the 2016 presidential election, they didn't get either particularly wrong.

[KeenFox]

Did they? As far as I can recall 538 has always been clear that they deal in probabilities, not binary predictions. They gave him a small chance of winning for a reason, and it turned out chaos favored one of the low odds scenarios.