Maybe the after-hours (AH) price drop has to do with:
1) Almost 6% run up in the stock during the regular trading day
(granted, the market as a whole had a strong rally too)
2) Although earnings were out of the park, future guidance seemed
mediocre/in-line (I'm just a beginner so I may be totally wrong but
I've learned the market cares more about the future than the past)
3) AH can be unpredictable... I was watching a stock (SYKE) last night
and it was up maybe 5 to 6% at most after announcing earnings - but at
least twice came back equal to the closing price(!) .... then today,
during regular trading it hit a high of 19.71 (a 23%+ gain from the
previous day's close)
4) Given the high number of short sellers that seem to be still in
this... maybe they are still in charge?