I agree that someone has to buy the mispriced stock. I disagree (because of evidence to the contrary) that someone can consistently identify the genuine mispricings in a way that pays off on risk adjusted basis.
Some of the big players have moves like that which work well given the right market conditions. My guess is that they have many, many patterns like that to trade on or models which are right more often than not. I don't know anything though since I'm a 101 retail investor... Positional options trading and volatility stuff makes my brain hurt :(
Have you seen strategies like that before? It's really interesting to dig into but seems to require a lot of knowledge to know how to trade on.
[0] https://en.wikipedia.org/wiki/Post%E2%80%93earnings-announce...
[1] Positional Options Trading: An Advanced Guide, pg. 90