A term coined by Bill James, who is a pioneer in baseball statistical analysis. From “The Bill James Indicators” page on Fangraphs (https://tht.fangraphs.com/the-bill-james-indicators/):

“Simply put, teams that improve in one season tend to decline in the following year, and vice versa.”

I think that describes, quite accurately, what is happening politically, worldwide, with civil and human rights. There has been an extended period of significant advances, and we are now going through, what will hopefully be, a short period of regression.