Think of him as the Kevin Kelley of politics. Mr. Kelley coaches football for Pulaski Academy in Little Rock, Ark. He’s gained national fame as the coach who almost never punts. Coach Kelley believes that remaining on offense (keeping possession of the ball) is more important than defense (trying to deny an opponent field position).

So he goes for it on fourth down even in his own territory. As a result, Mr. Kelley gives his offense four plays to gain 10 yards instead of three. Just as important, his all-offense approach gives his Bruins a psychological edge.

The strategy is not without its risks. Though Mr. Kelley says the math bears him out, his approach means opponents will sometimes score or intercept when they might not have otherwise. Backfires can be messy.

Mr. Trump is playing the same game. Not only is he always on the attack, he hardly ever backs down—even when he’s demonstrably wrong. The result has been a number of busted plays, whether it’s declaring that John McCain was not a hero because he was captured by the North Vietnamese, questioning the impartiality of an Indiana-born federal judge because the jurist has Mexican blood or his campaign team’s initial denials that Melania Trump had cribbed some lines in her convention speech from Michelle Obama when the theft was clear and obvious.