1) There's nothing stopping you from checking in WoL what they're doing damage to with Blade Flurry. And I will bet you any amount that the answer is cats, in which case you've answered your own question.
2) Even assuming you didn't check that, are you honestly saying that the Blade Flurry damage they do is so ridiculous that you think its more likely they've found some magical new way of using Blade Flurry or some hidden mechanic of the fight as opposed to just having a strategy that allows more cat damage than yours?
In short: this seems like sort of a ridiculous question.
Okey so I've been looking over some of the top DPSers on Majordomo heroic at worldoflogs and almost all of the rogues has done most damage with their Blade flurry and I can't imagine that only cleaving cats would make them do that much damage with Blade Flurry.
So is there any other mechanic that will make a rogue cleave something else during Majordomo heroic or how come they're doing most of their damage with Blade flurry?
If someone can explain this for me I'd be very thankful.