It's a good article, but it's all that you will find about them, no real details on how they are beating the markets over and over again. It's simply not possible to be that successful for so long. The article states that some experiments succeed and some fail and that their strategies peter out over time and they have to develop new ones. Okay, but never booking a loss?

Speaking as a former quant myself (1 year), I believe that there are transient patterns in the market.

The challenge is that those patterns appear and then they disappear mostly forever because they are frequently created by someone else's mistakes like Nassim Taleb buying way out of the money put options that never really created any significant profit. Free Alpha, get your free Alpha, right there.

To tap into those patterns while they are profitable, you need a lot of smart people, and a great deal of infrastructure for experimentation and delivery of strategies that can tap into those patterns before they disappear. While you're right that it is possible that they cheat, it's also possible that they have a sufficiently sophisticated infrastructure to actually make this work. It's kind of like how Nintendo only ships 1 out of 3 video games they develop. All IMO of course.