Did Bob and Franck confirm you they've always worked with the same hashrate, each hour, for all the reported days?
No interruption, no days with some miners on another pool, no maintenance, no windows updates taking hours, no sick GPUs ?

You may be right but just with the dates and payouts of previous days and the hashrate of last hour there's no evidence.

For the last ten days beta servers could also have played a role. Some users switched and other didn't.