Going to hold my tongue about xhash. I hope they do something to make this right.
I'm going to go with a stuck back-end, and hope that they go back through those 15,000% and 8,000% blocks to rectify the problem. I was mining on there with 40MH/s at the time and know for an absolute fact that my rigs were finding accepted blocks.
It is kimoto
Which has zero to do with the pool showing that two blocks took 15,000% of expected shares and 8,000% of expected shares when during that time people were seeing their rigs solving blocks, and those blocks being accepted by the pool.