Zacatecas damage assessment: PRD´s electoral disaster on July 4th

PRD certainly had a rather brutal defeat in Zacatecas, going from 46.40 percent to 24.6 percent - a pretty stunning drop.

Why did this happen, and what can the PRD learn from this?
The most important lesson, as the PRD seems to acknowledge, is that PRI-style dedazos will backfire drastically. The PRD's candidate was seen as an imposition by Governor Amalia Garcia, whose lackluster administration has been a deep disappointment, in particularly for those who saw her as a possible candidate for the presidency.

(We´ll talk about the damage done by former priísta, former perredista, and now ardent petista, Senator Ricardo Monreal later).

Yet also it shows the poor party loyalty from many of the nominal perredistas who bailed ship and actually supported the PRI candidate (himself a former perredista!), such as Raymundo Càrdenas.
It is understandable that there will be disaffection among the party base and elite under such circumstances. But it nonetheless illustrates the amazing opportunism among even long-time PRD cadres, who jump ship to join their old archenemy PRI.
What is to be done?