Something to remember about 2018 is the Dems had very significant spending advantages in almost all the close races. I believe quite a few would have gone the other way if funding had been more even. I’m guessing that the Dems weren’t pouring huge sums into many of these recent special elections, in part because the Presidential campaigns are now sucking up a lot of the funds.
The bottom line is, spending matters.
Vote Harvesting and illegal aliens put the SocialDemocrats over the top in 6 California House races. Orange County is Solid Democrat now. Thta is no way believable. Itr was a trial balloon for 2020. There was no reaction. It will be universal in 2020, possibly even overt. Why not? There is no penalty. The false counts are accepted by Republicans with barely a whimper and zero blowback.