4) Polling suggests Trump's bonus in the Electoral College (relative to the popular vote) is at least as large as it was in '16 (2.9%) or potentially even larger. He could plausibly lose nationally by up to 5 points (!) and still win reelection. https://www.nbcnews.com/politics/2020-election/how-trump-could-lose-5-million-votes-still-win-2020-n1031601

5) The asymmetry in modes of voting - Dems preferring mail and Trump voters set on in-person - creates additional and unique uncertainty, including potential for postal chicanery, voter error & rejected absentees that disproportionately hurt Dems. https://www.nbcnews.com/politics/2020-election/democrats-are-strongly-pushing-mail-voting-its-pitfalls-could-boost-n1235289

That said!! Biden's lead to date is clearly more *stable* than Clinton's was throughout '16, with fewer undecided/third party voters. I still view him as the favorite. And I'd welcome those tempted to label me as a "concern troll" to judge me by @CookPolitical's work in '18.

FWIW, despite what the state polling averages say, I still view Biden's path of least resistance to 270 Electoral Votes as MI, #NE02, PA and *AZ,* rather than FL or WI - based on demographic patterns and what we saw from hard votes in '18. Admittedly, it's a really close call.

And, just as there was a uniquely high chance of Trump winning w/ fewer votes '16, today I believe there's a uniquely high chance (maybe 3-4%) of a 269-269 tie, w/ Biden carrying PA/MI/ #NE02 and no other Trump '16 turf - a scenario the House would likely decide in Trump's favor.

One more thing: a lot of the factors I’ve listed are really hard to model/quantify! Especially using historical data that might not apply to recent trends.

Which is why I’m cautious of people who are really confident their quant models are super well-calibrated.