Interesting article. The middle really is all over the place.
But… these aren’t perfect little fixed points; they can move a bit. And, given two candidates, voters will need to pick one of the two*, so it’s a matter of whoever can position themselves such that the most votes (weighted by the Electoral College, so a rural Wyoming vote counts way more than an urban Los Angeles vote) come to them.
*Yeah, yeah. Two candidates positioned exactly in the middle with either no discernible difference or too many un-discerning voters. Whatever.