As mentioned in the previous post, when stocks have huge runs between earnings reports, any good news gets 'baked-in' to the stock price. Investors anticipate good news to assure that the recent price surge is warranted.
When earnings fall short of what's expected, then there can be a significant 'correction' of assumptions which translates to stock price. This is what we're witnessing in $FB as it looks to be retesting the lows after the data scandal (166.XX as of writing).
Nobody expected this -20% or more correction, but stuff like this is why earnings can be a (quite sharp) double-edged sword. On the one hand, when positioned correctly, you stand to win the majority of the time on earnings trades. On the other hand, these massive moves can happen and wipe out several winners. So long as you keep risk small and DEFINED, at less than 2% of capital, you will be fine, even after moves like this.
The market may now be pricing-in this cratering of $FB into $TWTR; I expect to see $TWTR down a handful of percent tomorrow. This may actually be beneficial to an earnings trade such as the one discussed in the previous post, but I certainly understand why somebody wouldn't touch that trade with a 10 foot pole.
Best of luck to all.