If the number of rshares suddenly increased dramatically, the value of all other posts would decrease significantly.
I haven't looked into the numbers, but this could be a factor as well.
For instance, if the @freedom account started using all of it's voting power, every post it voted on would be worth a ton, and every post it didn't vote on would see a huge decrease in its payout.
True. I was oversimplifying. But those sorts of changes will tend to average out over time. My main reason for commenting was just to note that that the pending reward value can drift up as well as down.