From Nieman Labs:
The top line takeaway from its analysis of 100 million articles is that social sharing is down by 50 percent across the board compared to just a few years ago. In 2015, articles saw an average of 8 shares; today that number has dropped to 4. Only 5 percent of content gets more than 343 shares.
There are several spins in that Nieman article that feel more like opinion. I do think that adjustments at Facebook are a likely cause of these changes but that also points to the overpowered influence the company has. I believe that if Facebook (and Mark Zuckerberg) were not getting so beat up in the public eye as a result of Russia tampering with the US election, then we would not have seen a change in their algorithm. In fact, I think this CNN article has it exactly backwards. Facebook is terrific at data analysis. It's like that they have been watching their numbers drop for awhile and only instituted changes that aligned with their perceived cause.
I read this statement by Zuckerberg differently than CNN:
"The world feels anxious and divided and that played out on Facebook," he said. "We have a responsibility to fully understand how our services are used and to do everything we can to amplify the good."
My guess is that Facebook has watched their engagement drop as the political climate has worsened. In times of high anxiety, like before the election, people turned to Facebook. In times of depression, like after the election, they turned inward.
Personally, I don't think Facebook is a good company. I think it's rotten at the top and at the core. I'm happy to see Facebook exposed publicly as the deceptive growth-monster they are. Now, if only we could do something about Google search now.