Why have those articles fallen in the rankings? The answer is simple --
Competition. Those who were once first have been incorporated by those who follow who have more fire and beans (bucks). Something's got to give. Being first once is not that difficult. Being first forever is the most difficult thing one can do. Don't need web metrics to look for answers, just look at all the one shot wonders in pop music from 1896-2019. :)
The web these days is more like Billboard 100 than the old days of "links" when the web was "new". Doesn't work quite the same way.
Producing "hits" (think songs on the radio) time after time is REAL WORK and requires all kinds of OTHER STUFF to make it happen. That said, decent income can be made from "ex" hits in perpetuity by keeping the "brand" alive with updates, new content, collateral content (images, text, audio, media).
Beauty of the web is EVERYBODY gets that first shot (compared to the music biz in this analogy) and that is something to treasure. And horde. And work like heck to maintain IF a "hit" happens. That original special thing can be milked for all it is worth. Reality is, that OVER TIME, that "song" passes to history because there are so many others coming along and a few (or many!) will shine brighter for a time. All things come to an end... after all Lennon and McCartney enjoyed 4 years... and yet remain to this day.
Rethink, regroup, and double down on what DID work and see what you can do to keep it alive regardless of what the competition is doing.
And always keep looking for other methods to monetize!