A normal change would not make your games drop so much. However the algorithm now and some time ago worked, it still is supposed to do some ranking based on interactions.
Since there are still games on top of the list, it obviously still sorts them somehow. But there are some massive problems behind the scenes. Servers are changing and I believe somehwere in Asia a whole section was cut off from parts of the hosting servers. There are threads about that.
The algorithm is also supposed to have some methods of preventing cheating. Maybe it is over sensitive to those behind the scenes problems. If they rerouted traffic it might have looked like artificial overinflation of view counts and was ignored, resulting in a lower ranking for some games.
Maybe it is some obscure bug, where only games hosted on a certain load distribution server were affected.
Other than that, a runaway self re-inforcing viral downward trend might be possible due to a small change in the algorithm. Like, you were on edge of page 1 and next day it was sligtly less visits so the algo puts you still further down. Rinse, repeat.
I thought it might have to do with updates, but then I saw a game on page 2 with no updates in a year.
What irks me the most, how the game of OP was apparantly at the bottom of some list. That is why I thought, and still suspect, access numbers were lost or counted as 0 for some time frame.