Seems like "Chet" has a few "friends" that "shift hopping"........causing all the lower hash rate miners( <100TH) lose some off their percentages for the current shift.
Makes one wonder just where they are getting their hash power. And why they all seem to join/login at the same time.....
Just saying.............
No doubt they've a method when to come/go, and how much work to do, to maximise profits..
Don't know enough about how the shifts etc work to have a guess at what that is, but if they're following the rules I suppose they aren't breaking them!