When Fox News architect Roger Ailes died last Thursday, one of the common threads through the coverage of his career was the ratings success he produced at the conservative news channel.

“Roger Ailes, who built Fox News into a powerhouse, dies at 77,” read the CNN headline. The Associated Press agreed: “He helped start Fox News in 1996 and built it into a conservative news beacon and cable ratings powerhouse.”

While Ailes was heavily (and deservedly) criticized over both the political legacy he left behind and the reports of serial sexual harassment that defined the end of his career, there was heated agreement within the press that Ailes was a television marketing master whose ratings success was untouched — and that the Ailes model would outlive even his own presence as at the network. (He was forced out last July as reports of harassment snowballed.)

All of which made Fox News’ ratings performance on the night Ailes died even more shocking: On Thursday, Fox News came in last place among the three cable news channels among viewers between the ages of 25 and 54. And it wasn’t a fluke.

In a development that has sparked murmurs throughout the cable news business, Fox News in recent weeks has regularly finished in last place among advertising-friendly viewers between the ages of 25 and 54, or “demo” viewers, as they’re known in the industry. (In terms of total viewers, Fox News does better, thanks to its large stable of viewers over the age of 54.)

“For first time this century, they aren’t in first place,” noted MSNBC’s Joe Scarborough last week. “In fact, for the first time this century, they are in third place.” Added CNN’s Brian Stelter, “This is an extraordinary moment in the cable news race.”

And yes, a lot of this is President Donald Trump’s fault.

Ever since Trump fired FBI Director James Comey on May 9, which seemed to then unleash an unending stream of breaking-news bombshells that rattled White House windows day after day, Fox News has seen its mighty ratings prowess threatened by MSNBC and CNN.

Basically, the ongoing and ever-expanding list of scandals involving the Trump administration — many revolving around Russia — has depressed Fox News viewers while simultaneously spiking interest at CNN and MSNBC, driving Fox into the ratings basement.

Are we witnessing a sea change in cable news? Or is this simply an extended blip that’s drawing back the curtain and revealing Fox News’ programming flaws — flaws that could be, at least in part, the result of endless personnel turmoil at the network for the last year.

Whether it’s permanent or temporary, the current ratings malaise certainly raises larger questions for Fox News as it confronts a key transition period and figures out how to cover the Trump administration. So far, its “defend everything Trump does while complaining about liberal media bias” strategy doesn’t seem to be paying off.

Keep in mind, last year Bill O’Reilly and Megyn Kelly were posting blockbuster numbers at 8 p.m. and 9 p.m. for Fox News. Today, they’re both gone and their replacement shows are struggling. Tucker Carlson Tonight is having trouble at 8 p.m., and The Five’s move to 9 p.m. has been, by Fox News standards, a ratings disappointment.

Carlson’s decline at 8 p.m. must be especially troubling for Fox News executives since it’s a valuable time slot the network absolutely dominated for more than a decade with O’Reilly at the helm.

Nothing Carlson has tried in recent weeks amid the Trump scandal season has worked. Tucker has tried downplaying or ignoring the pile-up of bad news for Trump. And he’s also tried claiming the scandal coverage is all “hysteria.”

Keep in mind, O’Reilly had posted some staggering numbers earlier this year for Fox News at 8 p.m. — numbers that, as of now, Carlson can only dream of equaling. (O’Reilly averaged nearly 4 million viewers during the first quarter of 2017; Carlson is routinely coming in 30-40 percent under those numbers.)

Carlson has also repeatedly finished behind CNN’s Anderson Cooper 360 in the 25-54 demo, and twice last week landed in third place behind both Cooper and MSNBC’s All in with Chris Hayes.

Overall, The Rachel Maddow Show at 9 p.m. has emerged as a ratings juggernaut for MSNBC this year, and especially this month.

Meanwhile, MSNBC’s The Last Word With Lawrence O’Donnell has toppedHannity several times at 10 p.m. – both in the key demo and in overall ratings. That’s the same Sean Hannity who, in the post-O’Reilly era, was supposed to be the network’s most powerful and influential attraction. Hannity’s “the alpha anchor right now,” Bloomberg suggested after O’Reilly’s departure.

But that hasn’t worked out.

What’s so shocking about Fox News’ ratings woes is how swift the downward movement has been. “Through the first six months of 2016, FNC is enjoying the highest-rated year in its history in total day and primetime viewership,” The Wrap reported last June.

One month later, in July 2016, Fox News’ implosion started when then-anchor Gretchen Carlson sued Ailes for sexual harassment. Since then, numerous key players have been publicly forced out at Fox, while others have walked away from the network.

I can’t say I’m shocked by Fox News’ current ratings slump. Earlier this month, in the wake of O’Reilly’s forced departure, which was then followed by the forced departure of the channel’s co-president, I noted that Fox was poised for some tough times: “I also think the drip, drip, drip of on-air changes and off-camera firings and departures could unquestionably alter the dynamics for the long-running ratings winner.”

That internal turmoil, coupled with Trump’s scandal-plagued presidency, which shows no signs of abating, could signal a new ratings era in cable news.