When S2 was looking for ways to make Heroes of Newerth worth buying, surely stat tracking was an idea not to be ignored! But where do you start? What is more important, kills or actually winning? And so it began, a vague question which would eventually spawn a debate even more useless then that of normal mode versus easy mode.
Every since PSR was willed into existence, it remains the only stat displayed publicly every time you join a game. This has created increasing amounts of criticism, especially from players with low PSR but comparably high kill-death ratio.
Advocates of KDR argue that KDR does a better job of judging individual skill- after all, a completely useless player can still win a game if his 4 teammates are skilled, right? Stats, after all, should be a personal judgement of skill, completely independent of outside influence.
There's just one problem with arguing this: it's impossible to do because Heroes of Newerth isn't a 1v1 game, it's balanced around 5v5.
Sometime after Arenas were introduced into World of Warcraft, Blizzard stated that 1v1 duels were not balanced. Many people questioned this statement- was Blizzard incapable of balancing a few classes? In truth, Blizzard made it clear that it was virtually impossible to balance team PVP with a set amount of classes while also making 1 versus 1 balanced using the same roster.
HoN suffers a similar fate. KDR is in fact not a perfect system of personal skill ranking. This derives a lot from the fact that certain heroes simply are designed to score more kills than others- in fact, in competitive Heroes of Newerth games, certain heroes are literally discouraged from scoring killing blows on enemy heroes unless they are the only one capable of doing so.
PSR on the other hand suffers from it's own unique flaws. As already stated, it is theoretically possible that a player who is lacking in skill can be carries by 4 other people. This theory, however, simply doesn't stand the test of time. No matter how good your 4 teammates are, eventually you will reach the point where 4v5 simply wont cut it anymore. I do not have any statistics to back up any points I make, you'll simply have to take it or leave it.
It all boils down to one simple statement: Neither systems are perfect; KDR is flawed due to hero roles while PSR is flawed due to teamwork- however, PSR is less flawed overall in determining personal player skill.
So where does KDR fit into this? Is KDR useless? Does PSR > KDR? Short answer: Yes. Long answer: Both count for something, PSR is the lesser of two evil ways to describe personal skill. Trying to create a "personal" skill ranking for a team based, teamwork dependent game simply isn't 100% possible.
...I for one am confident S2 will make "Wards placed" the only publicly displayed stat come next patch...