It’s a new model this year, as Nate Silver took his with him when he left 538. The new one seems to put a lot of emphasis on “the fundamentals” this far out, that is, it “thinks” that the general environment and economy and such is pretty good for the incumbent and that the polls might move in that direction by the time election day comes along. And since it’s fitted to historical data, it’s also implicitly assuming that this election will be similar to past elections (like, say, including a competent campaign by a candidate who can get out there and effectively communicate accomplishments and a plan for their term).

I personally think those assumptions are pretty clearly wrong this year and so I’m more inclined to base my perception of the race on pure polling averages, which are looking quite bad for Biden.