One would have thought that Fox News would be the big winner from a presidential cycle that began with 17 Republican candidates. Fox is now and was over the course of the election the most prominent cable news station among Republicans, with 44 percent of Republicans identifying it as their most trusted source of news or commentary in an October Suffolk University poll. Fox News was a go-to for Republican legislators and candidates well before the election campaign began.

That, as it turns out, may have been a problem. A study conducted by Harvard’s Berkman Klein Center released in August showed that the most effective media outlet at driving attention on social media wasn’t Fox — it was Breitbart.

Most popular media on the right from May 2015 to Election Day

There have been two overlapping trends that define the political moment and which, together, put Fox at a disadvantage.

The first is greater polarization. While Congress has been growing more polarized for several decades (driven largely by Republicans becoming more conservative), it’s only within the past decade or so that Americans have joined them. Pew Research has surveyed Americans on a range of policy issues since 1994; it’s only in the past decade or so that Democrats and Republicans significantly pulled apart.

As it stands, 95 percent of Republicans are more conservative than the median Democrat. Ninety-seven percent of Democrats are more liberal than the median Republican.

The other trend, which overlaps with the timeline of polarization, is the splintering of media sources, thanks to the Internet and social media. While television news had already fragmented during the growth of cable, there was still a substantial barrier to entry for starting a new cable station that produced news content. The Web, Twitter and Facebook obliterated the barrier to entry while simultaneously making it trivial to share information widely.

There’s another aspect to the issue of polarization worth highlighting. Not only do Democrats and Republicans more broadly disagree with one another on policy, but they are also much more likely than in years past to view each other negatively. Last year, more than half of Democrats and Republicans viewed members of the other party very unfavorably — with more than 40 percent saying that the other political party is “a threat to the nation’s well-being.”

It’s easy to see a marketplace that might emerge. We have a lot of chicken-egg issues here — Did polarization follow a splintered media environment? Does polarized news foster or follow dislike of the other party? — but there’s at least a symbiosis that allows for politically polarized media outlets.

Let’s layer on another common characteristic of the political moment: cherry-picking. I keep returning to an essay Lawrence Lessig wrote in 2009 for the New Republic. In it, he argued that there was a downside to making government documents public: People could use a surfeit of data points to cobble together speculative arguments. The best analogy for this is the strung-together conspiracy theories from the film “A Beautiful Mind.”

If you’re looking for something, the more you have to work with, the easier it is to find the pattern you’re looking for.

Once upon a time, Fox News had someone who did exactly that. Glenn Beck would create webs of largely unfounded allegations that impugned his political opponents and then rail against them for an hour a day. In 2011, Beck left Fox News, starting his own network. In an interview that year, former Fox News head Roger Ailes explained the thinking to Fox host Howard Kurtz.

[As] President Obama’s popularity has plummeted and the country has grown increasingly sick of partisan sniping, something unexpected happened. Roger Ailes pulled back a bit on the throttle. He calls it a “course correction,” quietly adopted at Fox over the last year. Glenn Beck’s inflammatory rhetoric — his ranting about Obama being a racist — “became a bit of a branding issue for us” before the hot-button host left in July, Ailes says.

The extent to which Fox actually let up on the throttle is debatable, but it’s certainly the case that Fox News ceded space to its right. During the 2016 election, Breitbart (and many others) happily nested there. That Fox was also the favored network of the Republican establishment — itself a remarkable victory for the network — worked against it in an election when the party’s base was clamoring for someone to challenge the establishment from both parties. Fox News still owned the airwaves, but Breitbart largely owned everywhere else. There was still space further to its right in the hazy, conspiracy theory land of Gateway Pundit and Infowars, but Breitbart became a mainstream force by being harder right and less establishment than Fox.

When he left the White House as a presidential adviser, Stephen K. Bannon returned to run the site, as he had before joining Donald Trump’s campaign in the summer of 2016. Bannon pledged to use the site to bolster Trump’s politics.

“Now I’m free. I’ve got my hands back on my weapons,” he told the Weekly Standard after he left, adding: “I am definitely going to crush the opposition. There’s no doubt.”

Over the weekend, Bannon demonstrated what deploying those weapons entails, sending two Breitbart employees to Alabama to, in the words of Axios’s Jonathan Swan, “discredit The Washington Post’s reporting on Roy Moore’s alleged sexual misconduct with teenagers.”

Consider what’s being described: an effort to cherry-pick information that can be used to bolster a largely partisan view that the allegations against Moore — involving attempted sexual contact with a young teenager — are invalid. Breitbart did indeed weaponize the overlap of online media and partisanship, and this is how that weapon is deployed.

(One of the first stories to result from this effort was headlined “Mother of Roy Moore Accuser: Washington Post Reporters Convinced My Daughter to Go Public.” This was an “exclusive” the site claimed . . . despite the point being mentioned in The Post’s original story.)

One of the things about the Internet is that there are large audiences for things that one might not expect. The example I like to use here is furries: Before the rise of the Internet, few people realized that there were large populations of adult Americans who enjoyed dressing up as animals. Now, there are furry conventions. The Internet proved the audience.

So, too, there’s an audience for news reinforcing partisan positions and negative partisan allegations. The universe is infinite; there’s always an audience closer to the poles than you realize. There was an audience last year for a theory that Hillary Clinton’s presidential campaign chairman was involved in a secret child-sex-slavery ring operated out of a D.C. pizza shop. It was a large enough audience that a guy drove across multiple state lines armed with a rifle to investigate.

When he got there, he learned that there was no such ring.

“The intel on this wasn’t 100 percent,” the man, Edgar Welch, told the New York Times. Which, as I’ve noted before, is wrong. The intelligence was 100 percent accurate: It just showed that there wasn’t any such conspiracy taking place. Welch wasn’t interested in that accurate intel, though.

There’s a market for political intel that isn’t 100 percent accurate in an America where nearly half of one party thinks the other is a threat to the nation — which means that someone in this splintered media environment will work to meet that demand.

It also means that there can be a temptation to drift further to the edges. Fox News’ ratings have recently rebounded from trailing MSNBC earlier this year, the Times reports, largely thanks to its reembrace of partisan politics.