so even if special election turnout or whatever is to blame for some of that, Rs are in trouble unless it accounted for like 7 points versus a general election.
...The thing is it likely did account for that difference, though?
In 2017/2018, virtually all the special elections except GA-06 showed far more substantial swings away from the GOP since 2016 than would actually materialize in November 2018. The November 2016 -> November 2018 swing wasn’t nearly as pronounced as the November 2016 -> special 2017/2018 swing. Why do you think that was?
If we apply the same 7-point shift to this cycle's special elections, you’d expect the specials to basically resemble or match the 2020 results even in a R+3-4 year, and, well, that’s what happened in most of them.