Donald Trump isn’t exactly on a winning streak, but he is beating the NFL in a rout.

The league’s commissioner, Roger Goodell, signaled the beginning of a messy, divisive retreat with a memo stating, “Like many of our fans, we believe that everyone should stand for the National Anthem.” Now he tells us.

The climbdown comes only weeks after a clueless bout of self-congratulation by the NFL and the media over widespread anthem protests. Donald Trump doesn’t play three-dimensional chess, as his supporters insist. But he does have an instinctive cunning and a grasp of a nationalistic cultural politics that shouldn’t be underestimated by his opponents, even though it almost always is.

It’d obviously be better if a president of the United States weren’t waging war on a major sports league. Trump’s intervention has been inflammatory from the beginning. He shouldn’t have called protesting players “sons of bitches” and mused about firing them like the loudest guy down at the end of the bar.

The very outrageousness of Trump’s initial riff, though, served his purposes. Trump’s lurid overstatement acted as a neon advertisement for his commonsensical underlying point, namely that players should stand during the national anthem. And it baited the NFL into fighting him on indefensible ground.

There were all sorts of unobjectionable means available for players to defy Trump, but they allowed themselves to, in effect, get double-dared into disrespecting the flag.

The perils here should have been obvious. David Frum, an incisive and unrelenting anti-Trump voice, wrote a piece for The Atlantic at the outset of the controversy, urging players not to cede the flag to Trump. They went ahead and ceded the flag to Trump. Why?

It was, in part, a classic bubble phenomenon. Sports journalists are, if anything, more left than political journalists. They were excited about being at the center of a national political debate and sticking it to Trump. Much of the media piled right behind them. On CNN and MSNBC it was rare to hear a commentator say a discouraging word about the protests, let alone warn that the NFL was stumbling into Trump’s political kill box.

It is true that, after Trump got involved, the polling on the protests showed the public more evenly divided. This doesn’t have equal significance: If you’re Donald Trump and at 40 percent or below in the polls, a 50/50 issue works for you; if you are the NFL and trying to appeal to a broad audience, a 50/50 issue is a disaster for you.

The NFL misunderstood its own nature. It’s not just that it is a game that should be a respite from political and social contention; as a quasi-national festival, it should be identified with a certain baseline of patriotism (the national anthem, the enormous American flags on the field before games, the military flyovers, etc.). Colin Kaepernick cracked this image, and Donald Trump drove a wedge through it.

It is much too early to know what the 2020 landscape will look like, but if Trump wins again, it will surely have something to do with a dynamic like the one that played out with the NFL. Trump will cause an unthinking overreaction by Democrats on a culture issue or issues, and the party will be wrong-footed by the insularity of its own political and media ecosystem.

What most repulses Democrats about Trump, his status as a nationalistic culture warrior, is what they most need to take heed of. If Hillary Clinton during the campaign had said, politely, that Colin Kaepernick should stand during the anthem, it might have been enough of a signal of old-school patriotism to working-class voters to put her over the top. Three more years of Trump will presumably make it even harder for the next Democratic nominee to tack to the center on a few cultural hot buttons.

The NFL’s agony is the Democrats’ peril.

Rich Lowry can be reached via e-mail: comments.lowry@nationalreview.com.