On the day after the Indiana primary confirmed that Donald Trump would be the Republican nominee for president, Kathleen Parker of The Washington Post was looking elsewhere—back a couple of days to an event that had happened during Ted Cruz’s final, desperate attempt to seize a chance at the nomination for himself. Out of that desperation, Mr. Cruz had announced that, if nominated, he would choose Carly Fiorina as his vice-presidential running mate. Accordingly, Ms. Fiorina was introducing the Cruz family at an event in Lafayette, Indiana when, as they were entering the stage behind her, she briefly fell off it. From the video, it’s pretty clear that the candidate himself didn’t see this happen, though his wife did, and helped the would-be veep, who was unharmed, back up onto the platform in time to give her husband a hug when he arrived at the microphone. For a brief moment you can see Mr. Cruz glancing to his right to see Heidi pulling Carly back up, though he does not otherwise register any reaction to her fall. For Ms. Parker, that one glance was enough.

One second, you’re a candidate. The next, you’re a cad. Whatever Cruz has wanted voters to think about him—the qualities and character that can’t be gleaned from a résumé—he lost control of the narrative. His reflex in