What does it tell me? (And I believe it to be likely true.)
1. This 'historic opportunity to elect a Democrat, if only we get some centrist who doesn't offend anybody' routine is crap. We need candidates who stand for something and who are forward-looking rather than nostalgic to drive voter turnout -- both in the primaries and in the general election.
2. Congress still gets low ratings, and active membership AS DEMOCRATS is not growing so much. There is a huge lack of trust out there, which extends to the Democratic leadership, corporate mainstream media that generally endorse Democrats and many sorts of stereotypical Democratic politicians.
3. Corporate Democrats buy all sorts of pollsters and number crunchers and few are as dumb in their choices as Hillary was. (EVEN If some of that miserable crowd have found jobs for this cycle.) Biden knows the general score. So do Schumer, Pelosi, Cuomo, Hoyer and so on. So Biden starts to tack a little, in such predictably quarter-step ways. Those who continue to say that issues don't matter will disappear. And voters coming out of the woodwork who don't adore the old Democratic leadership are why there is the DCCC blacklist against activists and consultants not under their control, the complete phobia in the Democrats Abroad global leadership against anyone and anything that might disrupt the old social circle and that same sort of thing in state party after state party.
4. In the face of this a whole lot of money has been spent on vilification and there will be an awful lot more. We can't ignore this but we need to snipe with great precision rather than throw bombs in response. Boris and Natasha jokes are fine, but the use of the word "Russiagate," the indiscriminate identification of Republicans with Putin, screams of "treason" and all of that need to give way to more sophisticated and constructive critiques. We need to deal with FOREIGN INFLUENCE and both the perception and reality that foreign powers can buy access or influence -- not just the Russians, not just the Republicans. Progressives need proper mixes of scorn and alternative proposals to respond when the energy, pharmaceutical, insurance, firearms and so on lobbies go after us. One of the stupidest things that Democrats could do is become mirror image insulting and slandering blowhards like Donald Trump.
5. 'It's in the bag -- we are the presumptive next government' is a message we should let anyone stupid enough to make in the primary make. We on the left side of the party ought to just prove that this bandwagon stuff isn't true. The screeching 'WE'RE IN A CRISIS AND YOU HAVEN'T SENT MONEY!!!' stuff that's the hallmark of DCCC / corporate Democrat email campaigns we need to actively and more creatively mock. And it HURTS the Democratic cause to give money to people like this -- donate to individual candidates and groups with agendas to which you can relate instead. In the general election campaign expressions of complacency should be treated as enemy propaganda.