I had thought the same thing on a simplified basis, although as I think more about it, I gotta wonder how much down-ballot success is due to extreme gerrymandering than it is to their general message ex-top of ticket. The Dems did pick up three seats, but those were vacancies. The Republicans did not lose a single contestable House seat out of the 220 they held, and they actually picked up a couple Senate seats. So I'm not sure how much comfort I can take from the down-ballot argument anymore.