It’s a chance of winning, not a poll, so 64% is high but not insane. Silver is serious and it’s a decent model. Knowing the model there’s a pretty good chance this is a high point for Trump but it’s not like he’s pulling this out of nowhere, he has had similar models every election cycle since like 2008.

If it’s overstaying Trump it’s because his model is interpreting the data incorrectly because of the weirdness of this election cycle. I personally think that is likely the case here.