Really successful traders spend their obtaining insider information, not massaging public data. It stands to reason that an ensemble of technical trading methods would regress towards the mean.
Nik Cubrilovic recently demonstrated how information leakage can be used to trade stocks, eg estimating the growth rate of the Adobe Creative Cloud customer base based on assigned customer ID numbers, before Adobe announced the figures themselves:
http://www.itnews.com.au/news/how-an-aussie-hacker-used-info...
It was more subtle than inside information. He implied that he could actually influence the outcome and hurried me on from that point.
Mind blown.
For example, http://priceonomics.com/the-trade-of-the-century-when-george...
What did Soros know about what would happen and what did he actually cause to happen? The story sounds nice on the surface (I made a multi-billion dollar bet on a quote from some guy - lol), but I wouldn't be surprised if there was some back channelling going on.
Sure, there are a few that do illegal things (and inevitably get caught since there is so much monitoring going on).