Absolutely no way it'is bug, for sure. It can't be if the pool exchanges cryptoes internally, take a thought  But I assume it just shapeshifts (search the topic) bulk to bitcoins, then shapeshifts some BTCs back to the desired amnt of alts. And it can't be bug, too: as Shapeshift's rates r really poor in comparison, can't see a reason for a pool mngr to use it other than bonus or alike. Especially keeping in mind the question have been raised in this topic many times. Bug, eh?

I can understand ur antimonies: BTC-lovers as u r loose just few % more feeling ok with it, but for alts it's incalculable (!) breakdown as spread is huge for half of, u know. I know how to deal with alts I mine, but loosing 2% pool fee, not 10-20.