Why did Sheryl Sandberg leave Google to become Facebook's COO? Let's be real: Even if Facebook one day grows into its $15 billion valuation, it's unlikely to unseat the world's dominant player in online advertising. Sandberg had a great gig running AdWords, the engine of Google's profit. Her job had only two drawbacks: sales chief Omid Kordestani and Shona Brown, head of business operations. Sandberg disliked those two executives enough to be open to Facebook's approach. Mark Zuckerberg, a suggestion on how to spend a very small part of Microsoft's $240 million: Send Kordestani and Brown thank-you gifts.