In one of Dota2's recent patches, Valve has added a new feature called "Performance Index" visible in your own in-game profile.

It is not clear how it works. Is there any information available, what "performance" it monitors? 
Does it rely on `K/D`, `K/D/A`, `Gold per minutes`, `Experience per minute`, or all of them?

![Example for Performance Index][1]


  [1]: https://i.sstatic.net/F9eqH.jpg