1) In the Trump era, a month is an eternity. Between now and election day, Trump could nuke South Korea, now that he's in love with Kim Jong Un.
2) Measures of "enthusiasm" are difficult to assess. Every vote counts the same as every other, within the same election. One of the arguments is that Republicans are so jazzed about having a rapist on the Supreme Court that they will turn out when they otherwise wouldn't. Maybe, but the question is whether enthusiasm grew among the Republicans who otherwise would have voted in an unenthusiastic way, or among the ones who would have stayed home, and that's a hard question.
3) Money. Money matters in weird ways for congressional elections. It helps challengers, and does very little for incumbents. Money has been flowing freely since the Kavanaugh stuff started, but that means it is difficult to assess its role until we get a clearer picture of how much we are talking about, and where. But, it's there. What matters is how much and where, and that we still don't know. Developing story.
4) Underlying everything is Trump. Midterm elections are always about the president, and Trump remains unpopular. RealClearPolitics average approval rating right now is 43.6%. However, we don't know how that plays when, a) the economy is booming, which usually translates to high popularity, and b) the president does nothing but hold campaign rallies. That second part matters. Part of the midterm effect is that presidents generally don't campaign as actively as during a presidential election. Of course, his campaigning isn't properly targeted because it's more about his own fragile, little ego than the party's electoral fortunes, but it is there.
Right now, we are seeing narratives develop about how the 2018 election will be either the mobilization of evangelicals because of Kavanaugh, or the mobilization of women because of Kavanaugh. Post hoc ergo propter hoc, the election happened after Kavanaugh's confirmation, therefore the result was caused by Kavanaugh. Um, no. That's not how logic works. Watch the money, watch for any deviations from the turnout that would be expected in a midterm with a president at 43.6%, and keep in mind that an unpopular president with a booming economy is a split that messes with everything anyway.
And next week on The Trump Show, something crazier will happen. How do I know? Because we live in a reality show with scripts written by coked-up idiots who are always trying to top themselves.