I had a thought as I read your very accurate analysis. It just might be that the "mushy middle" doesn't like politicians who are in the mushy middle. They're the ones who won't fight for themselves. Perhaps for that reason they like pols who will fight for them.
Could that be part of the reason President Trump did better than expected with them?
You may have a point.
My elder son is “mushy middle”. He is generally conservative, but doesn’t really follow politics. He didn’t like Trump in the primaries, but then he didn’t really like anyone in the primaries. He didn’t trust Hillary and ended up voting for Trump, even though he found him personally repugnant (more on that later) he thought he would get stuff done.
He had a low opinion of Trump because he barely follows any news - typical mushy middle cares only about what is going on in his immediate surroundings - and the only thing he kept hearing about was how badly Trump treats women. Even though it wasn’t true, it was repeated enough times by the left that even someone who doesn’t watch the news or follow politics came away with the impression that Trump was a lewd cad.
We will never win this fight unless we can do something about the left leaning press.