Ted Cruz did what he had to do. Donald Trump fell well short of the shock-and-awe moment he hoped would set up a blitz through the rest of the country. Marco Rubio bought himself a seat at the big table. And Hillary Clinton flirted all night with disaster.

Those were the big story lines that emerged from Iowa’s caucuses Monday night. It’s early—ridiculously early, actually—to draw too many conclusions. But the results suggested that a fight still lies ahead on the Democratic side, and a potentially much bigger and longer...