If FB's initial analyst communications emphasized optimism over credibility and deliverability, or FB was impatient with questions casting doubt, the analysts may have had reason to start with high estimates. The May 9 filing comes out and reveals those to be implausible, and they have to dial back to avoid looking silly or as if they're pumping the stock.
If FB management hadn't spent a lot of time thinking about the relationships between the analysts and the investors, they may have missed the point that those investors are the analysts' ultimate clients. If they didn't spend much time with the analysts, they may have neglected building relationships where they could subtly signal issues without tripping regulatory problems.
Or the analysts were idiots and screwed up the biggest assignments of their lives.
Is all this shady company / banker / investor communication good? No, but this is how it's done right now, and if you want your partners to do well you have to work within the rules of the road. It isn't clear to me that Facebook took the time to do that.