One fact I read from the very fist posts of the DRK thread is someone was selling 40000 DRK for just 1 BTC. Quite sure he is not the only one holding such amount of coins at that time. DRK can be easily mined at the beginning. The rising of BTC price is partially due to reward halving. So once Dev "intentionally" reduced the reward, no wonder DRK can get high. Pretty normal. X11 & DarkSend are just boost of the rising, nothing much significant than this.