I am not sure I can look at a history of hash rates but I think QdXXBSJNcVYnjWm57KVL797typum4JZ5fe had a significantly higher hash rate in the recent past. This address/worker is still getting more work even though his or her hashrate has dropped, because of the lookback period. The pool has 6-8 MH/s in the not too distant past but I am not quite sure how to see the history of worker hash rates. This address isn't my own unfortunately.
History of hash rates:
http://blackpools.pw:3333/static/graphs.html?MonthThat address has always received half of the block value or more with mediocre hash rates. It's really weird. Let's see if your changes make the rewards more fair.