I was also curios about this system and i found that everyone is talking about this. Even if you will check new reborn version then you will found that now they are giving you full list of heros with their win, kills, last hit, how much you farm, how many rampage you have taken with which hero bla bla bla..
Even you can compare yourself with your friend with new chart so they are continuously changing the performance algo and no one knows how it works..People said few point about how it should work but then people are also commenting points by which you can say that you are not sure..Please read this to know little bit more info..
I think performance of players should give more relevance to other stuff than just kills, deaths and assists (k/d/a). It should also take in account spending on support, damage done to towers and buildings, healing/support skills used, damage dealt to heroes and some individual stats depending on the hero picked for team battle oriented heroes (like number of simultaneous enemies captured by and ulti for enigma or number of heroes that get in contact of the wall for Dark Seer).
The most crucial for me should be damage on buildings and spending on support, because these are stuff that should be encouraged and are really under appreciated on stats.
I get that k/d/a is a really compact way to rate a player but it should at least have two more key values like k/d/a/bd/s where bd can be a calculation based on Building Damage done per game and S a calculation based on Support per game, where the values are weighted to produce a reasonable scale!
The Building damage would encourage push strategy and should have a relation between damage done and the time in the game that it was done, that would encourage fast push strategy without discouraging K/D/A, because those would add stats also.
For last the support value should take into account stuff like gold spent on wards/gem/dust/smoke/courier/fly courier, the times in the game that it was done and the support items bought and their use (mechanism heal, pipe damage taken, and stuff like that).
but then if i will go with this then please have a look on this too :
"Honestly the closest way to do something like this would be to simplify the hero categories, but even then there are just too many things to consider. They already have a multi-star system for each type of role, more stars meaning they are better at that particular role, but almost every hero has multiple roles, some as many as five. With that many combinations it makes sense to say that a hero can be played more than one way.
A hero like Necrolyte is listed as "Support, Durable, Carry". Well what is he? That depends on the person playing him and the items that are built. Personally I do play Venomancer as a carry, and rarely like a support. My KDR with him is naturally going to be higher than the majority of people that play him as a support and build completely different items and play more of the support/babysitter role. Does that mean I'm going to look like one of the worst Venomancer players because I don't typically ward or buy a courier upgrade or dust? A lot of people find it enjoyable to play heroes outside of their role, so can we base a rating system by role if people are not going to follow "the rules"? What good does a rating do if you lump heroes you play like carries with the other carries based on item builds? What are you comparing it to? As much as it would be nice to see how well people do playing heroes based on support, durable, carry there are just too many ways to step outside of that role and negate the rating because the rating would only be looking for certain stats for certain heroes. Supports would ignore things like KDR and GPM but instead maybe assists, wards, denies, and consumables.
There are just too many things to look at and at what point does the system get so complicated that most people simply cant understand it? Perhaps a tab for each hero that shows each of those roles (what, like 9?). Have a "Jungle" tab that shows your jungle creep kills and a "Support" tab that shows wards and consumables and other related information important about the role. Could do that for every hero to get an idea about how you play that hero personally, but most people wouldn't have much good to say on the Carry tab with Earthshaker or Crystal Maiden (I know I wouldn't). There would just be a lot of useless stats generated by trying to categorize stats per hero by role in my opinion.
Something would have to change or a really good implementation would have to be created for it to work. I would like someone to figure out a way to categorize players by this though more-so than heroes, and let people display who they are. "I'm a support dammit, I do all the hard work so we can win the game", or "I'm the carry, I like farming and killing stuff." Just a few thoughts."
Ref : gpardini00(dev.dota2.com)
So simply you can't say YES i know how it work and all we can think is just think..that's it..
But will try hard to find the solution and sure will give you. hope you will get some point by this and read at least once :P . :)