Hmmm.....interesting. There is obviously a lot more involved than simply buying straddles mechanically before each earnings cycle. Current market volatility being one important ingredient, for example.
Also, the annualised figures are a misleading positive statistic. Each trade lasts 6 days, and there are only four earnings in a year, so a person can only trade AMZN (say) for 24 days of the year using this system - there is no way to 'annualise' this and trade AMZN for 365 day.