For better or worse, Kasich has become the vessel of moderate Republican voters: the suburban, upper-income folks who prefer pragmatism to bomb-throwing. And Carly Fiorina is, at least rhetorically, a Cruz-style firebrand.
There’s also the fact that pragmatic conservatives tend to favor someone for veep who has deep experience in governing and legislating, something that Fiorina does not.
In other words, Cruz picked one of the few people in the 2016 field who will struggle to appeal to Kasich voters and unite the GOP around Ted Cruz.
Maybe that won’t matter, given Fiorina’s intelligence and rhetorical verve. But there’s just as much reason to believe that Fiorina pick will drive Kasich voters further away from Cruz, at precisely the time when he needs them.
In which case, Cruz is toast.