When it comes to balance, keep in mind that immature & unexchanged are just estimates in BTC as their name state. If the market go down, your immature & unexchanged coins worth less.
Yes I know, and that's exactly my point, if the coins had been auto-exchanged like the pool states, then I would have gotten the original amount stated, rather than the decreased amount that happened when the value of the unexchanged coins went down.
I don't think anyone can predict a coins value in advance. If you can then by all means please do.

Lol, I wish I could predict the future price of a coin. But I'm not asking about future prices, I'm asking about the current estimate. If the current estimate says 1BTC then I should get 1BTC if I trade it right then and there. But if it says current estimate is 1BTC and I don't trade it then, then the value can go up or down, and in this case it went down since it wasn't auto-traded when it was the original estimate. I hope I'm making sense.
As it states, it's an estimate based on the last known price... it does not predict the future. ex: last trade @ 0.05 with a volume of 1000, then nobody want it @ more than 0.04. You may want sell your coins as much as you want @ 0.05, if there is no market to buy them, you will have to wait or lower your price. Then you want to get the best price, but so other guys don't care and sell @ 0.04... and there we are, the last price fall @ 0.04, and your estimate go down.
Conclusion, H2O keep the coin unexchanged longer to get a better price if possible... and if you look closer, you'll see that the red line increase usually more than the decrease in unexchanged coins, which is the sign of a good trade.