If Trump does win by 14, I can't see how Blunt doesn't win.
Coattails aren't really a thing, though.
Repeating the same thing multiple times doesn't make it true. Blunt is just lucky that he's running in a n increasingly red state. If he were running in a swing state, he'd likely get Blanched.
If coattails were a thing, Heitkamp, Manchin, Donnelly, Collins, etc. wouldn't be Senators today and Blunt would be winning in a landslide. Granted, red states are more likely to split their tickets and vote for a Democrat for Senate or Governor than blue states, but still.