People forget how unpopular both of these candidates are. Trump is such a bad candidate that split-ticket voting will be at record levels by default, like in 1996. Most incumbents simply don't lose by wide margins, unless they're Blanche Lincoln.
In 2008, there was a backlash against pretty much all Republicans and the entire GOP. That is not the case this year.
No one said anything about wide margins. This is also not 1996. The Republican Party will not be able to detach themselves from the nominee no matter how hard they try. You're only fooling yourself if you think that's possible.
Also there's no denying Democrats have higher turnout in presidential years. That, combined with a potential depressed Republican turnout (there's real evidence of this), anonymous backbenchers like Blunt and Burr can get washed away in a wave.
