I have family in Kansas, so I'm allowed to use Subjective Analysis™. Kansans are quite conservative, but also quite modest, so I wonder if Kobach doesn't seem like a bit too much of a showboat for them. And it actually wasn't even all that great a state for Trump, who fell off relative to Romney's vote share there. Plus, there's a lot of disillusionment with Brownback and the ultra-conservative wing of the GOP.