a 5 point win here won't be terribly promising for Dems in 2018.
Was John Bel Edwards 13 point victory a sign that the GOP was in trouble in 2016? Not evidently so. Gubernatorial races are less susceptible to partisanship than federal ones, so drawing conclusions based on one for the other isn't very sound.
Part of JBE's strong victory was that Vitter was a horrible candidate, and that prostitution scandal destroyed him. But I agree, gubernatorial elections are less susceptible to partisanship, but also far more likely to be affected by state-level issues, too.