I agree with Paul’s assessment of Ted Cruz announcing Carly Fiorina as his running mate. But I would go farther: the move is widely seen as one of desperation, and tends to cement the perception that Cruz’s chance of winning the nomination is slipping away. Fortune’s take was typical. The magazine first headlined, “A Desperate Ted Cruz Tosses a Hail Carly,” which was then softened–a little–to “A Fading Ted Cruz Tosses a Hail Carly.” Has early selection of a running mate ever worked to change the momentum in a race? Maybe, but I can’t recall an instance. Which stage of...