The departure of star Facebook director Ben Ling has been roiling Facebook since word first spread at the social network's Palo Alto headquarters yesterday. One inevitable question some Facebookers are asking: What does this mean for the price of our stock? If Facebook were publicly traded, it's unlikely one employee's exit would cause a blip. But private tech companies like Facebooks are the ultimate growth plays, and momentum matters. If Facebook becomes known as a place top talent flees instead of gathers, it could tank Facebook's perceived value. What will be telling: Who leaves next, and how fast. One likely candidate: Chamath Palihapitiya.Palihapitiya, like Ling, has not fared well under the reign of COO Sheryl Sandberg and her right-hand man, Elliot Schrage. Schrage, as a reward for the puff pieces Sandberg's continued to garner from a mostly pliant press corps, has gotten handed most of Facebook's marketing functions. Palihapitiya has been left with a vague "growth" portfolio. How frustrating this must be for Palihapitiya, who once complained on film about white-male privilege. His employer at the time, the Mayfield Fund, hastened to clarify that his comments were about the world at large, not meritocratic Silicon Valley. But Elliot Schrage, with his two Harvard degrees, is a creature of New York and Washington, D.C., not the Valley. And he has blocked Palihapitiya's rise at Facebook, despite the latter's vastly more impressive tech résumé. Will Palihapitya rest and vest his Facebook shares in silence? Or will he leave, like Ling?