Same shit has been happening to me too ! I just tell em I can't control the pool your using. It's quite obvious by looking at the charts your showing it's the pool side.
I've also noticed that when the time is up the chart still goes for a little while which in turn brings the average hashrate down because obviously the hashrate is 0 because mining was over lol I had a guy leave me a 4/10 rating because the hashrate dropped after his time was up the average went from ~5.1 to ~4.6
Yes I've just realized the charts are using the ramping up/down period of the rentals in the average calculation inserting a bunch of zeros into the equation. I think somebody failed stats 101.
A simple solution would be to truncate the first and last 5 minutes.
Anyway, I'm mining straight drk now, the difficulty has dropped and I'm making more than renting. If theres a pump in a few days rental prices should rise and then renters will be blinded by greed and not nit pick.
I still cant figure out why a person would spend 0.1btc to rent a rig to mine 4 drk coins when they can just buy twice as many directly.