We have to explain ALL the losses

[mythology]

24. I wouldn't argue it is meaningless

I would wager that if you live in a district that is heavily one party or the other on all the down ticket races, you would be less likely to turn out to vote. For example I had 4 "races" on my ballot this year. I put races in quotation marks because 3 of them were Democrats running unopposed. If I were a Republican and looked at my ballot ahead of time and saw I effectively didn't have any choices, I might not vote. It's not like Trump was going to win my state.

Put that in the context of a red state where it combines with not just gerrymandering, but also reductions in polling places where minority (read Democratic) voters vote and reducing early voting, it adds up. Trump won by less than 1% in Michigan, Wisconsin and Pennsylvania. Those states have pretty consistently voted Democratic in the presidential races while Republicans have gerrymandered state districts to their advantage. Which in turn means when somebody is running for say state Senate, a Republican candidate is more likely to be running after having been in the state House and thus have a built in edge in terms of name recognition and fundraising apparatus. That effect would inherently be delayed and hard to measure, but over time would lend itself to more Republican candidates winning.

I don't have numbers to back those up, and could be completely off my rocker, but when our elections are trending to be closer and closer, coming down to a handful of states and we are now better able to predict based on demographics how somebody will vote, it only takes a small edge to win. Trump won by less than 100,000 votes spread over 3 states. Bush by 500 in one state and then a bit over 100,000 votes in Ohio.