I was looking at NPC kills, PVP kills, and DBS drops today. I noticed that the drops really don’t seem to connect directly with NPC kills. Like I found a system(U-F in PF) with 23k NPC kills, one of the highest for the last 24 hours, according to in-game map/dotlan, and it only dropped like 6%. While other systems did 4k NPC kills and dropped 7%.
The pvp amount is very little, like 2 ships or 0 ships in some of these systems as well.
CCP will likely never explain how the calculations are specifically done (or even suggest certain things beyond what they’ve already said in the devblogs) to prevent people from figuring out the exact methods and game the system.
Whilst we can never know, I suspect amount of ESS thefts and for how much is a contributor as each theft destroys a proportion of the bounties. Also of those thefts, how much of the ISK plates actually get back to Jita and are sold? Some thefts can result in 100% of the reserve bank value being lost