Script altcoins plummet because there wasn't good inovation, when ASICs are intorduced.
X11 ASIC would just replace GPU miners. DASH's core character is masternode.
After pump, ...direct dump always in altcoin world.
With bitcoin the ASICs caused a huge increase in bitcoin price. I guess it could also be the rise in price that caused the ASIC production.
The scrypt algo was targeted to be ASIC resistant. As soon as an ASIC was designed, this benefit was lost. That was likely the cause for the drop.