when they did the minimal amounts of real polling at the end, the polling was massively skewed towards the democrats, in terms of sampling. the results the media reported were not a correct reflection of what the polling said. i accurately corrected the news reports that inaccurately reported on the polls and my projections were what the polling actually said.
the media's projections of the polling results were in fact broadly wrong (because they misread the data).
however, the fact that republicans didn't show up to vote recreated the skew in the data. it was not good modelling - it was mostly terrible modelling - but it was just dumb luck. it should have come out in the wash, but it accidentally worked.
that's why they have the elections.
are the democrats going to hold these seats? i doubt it. if they do, what's going on is more like realignment than political shift. as a socialist, i wouldn't vote for most of these candidates for local dogcatcher. these are people, almost without exception, that i would go out and campaign aggressively against. i don't agree with them on anything. and i think they're ugly and gross people i wouldn't talk to at a party, too.
as a result of this election, democrats are going to be more likely to oppose women's rights and more likely to oppose queer rights, while being more likely to support using the state to enforce religion and less likely to stand up for jews. this is threatening to pull the party into the contemporary dark ages of the conservative movement. it's not a swing to the left anywhere in any sense and will not result in more equality, more liberalization or anything approaching it, anywhere.
the democratic party may have won but liberal democrats and liberal democracy massively lost. the victors are the religious right and the increasing normalization of conservative value systems.