As I"ve been instructing folks, the ways you would evaluate a normal election with the number of voters increasing relatively in the same percentage as total population growth, just don't work here.
We had two UNPOPULAR, virtally UNLIKEABLE candidates running against each other. Neither got anywhere near their party's historic high!
It's pretty clear that there are unhappy people somewhere ~ obviously Conservative Republicans are unhappy with the GOP_e, but what Democrats are unhappy? Maybe we might look at the House of Representatives elections and the state legislatures to find who those unhappy Democrats might be, and what we might do to CONVERT, en masse, their faction to the GOP.
Whoever they are they've not been showing up to vote for Congress-critters or members of the legislature. Could they be retirees? Maybe they're Democrats with a college graduate living in the basement! Whatever, except for the Obamista faction, the Democrats are definitely not winning all the elections ~ and you and I are old enough to remember when Democrats used to expect to win everything.