My thoughts: competition. Nasty used to be the only tradable managed group buy that was currently hashing. LabRat now has higher yields, so their prices are going up and Nasty's are coming down probably until the yields meet. LabRat's price raised to lower the annualized yield to 20%, Nasty's price fell to raise the annualized yield to 28%. So it looks like labrat was overbought and Nasty was oversold (although LabRat has promised hardware to arrive sooner than Nasty's Monarchs). Nasty also has debt while LabRat used equity to make pruchases.

However, OgNasty sounds like they are considering diversifying. He's already sold some physical objects for nastyfans (1g coins) and they are one command line argument away from running their own pool -- they have all the infrastructure in place.

I'll personally keep some seats since I've seen OgNasty make some good decisions for the benefit of bitcoin and the network, to him it's more than making money and I'd like to promote that. It's worth a couple bucks to me to see that continue and be a fan of it.