Is there an easy explanation for that drop?

Easiest explanation is the drop in price, but that doesn't account for the full loss. I'm sure the rest has to do with the number of people voting, the number of votes being cast, and the amount of influence being used.

How exactly it all pans out, I'm not sure.

For the record: I was not in favor of the changes. I wanted less than squared but more than a full linear algorithm. And I was completely against changing the vote target to give people 4x upvote power. Both of these completely disregard the abuse mitigation protocols that were in place...and even worse - they came after the 4-post reward limits were removed. But it seems that nobody wants to listen to common sense, so here we are.