In a word: turnout. While the Democrat lost Tuesday night, he only lost by seven points, while, in 2016, the Republican won by thirty-one points. Kind of a big swing.
But, as always, there’s a numerator and denominator to worry about when comparing percentages. And that’s really bad news for Republicans. Comparing 2017 to 2016, the Democratic vote total dropped by a third–not unexpected in an off-year, special election. But the Republican turnout dropped by nearly two-thirds, reaching only 38 percent of the 2016 Republican vote total.
There might be an enthusiasm gap.