What is that rating thing in stats?

Many of you have been wondering what is the rating we recently introduced to the stats section and how it's calculated, so here it goes.

Kills/Deaths (K/D) ratio is usually recognized by people as an indicator of how good a player or a team performance was, and it is a solid indicator in around 75% of situations. However, it is faulty and unfair in other situations, so with that in mind, we wanted a more solid indicator, so we introduced the Rating.

How is Rating calculated?

Rating is calculated by comparing a player's average stats...

• kills per round
• survived rounds per round 
• a value based on number of rounds with multiple kills

...to the same averages for CS in general (which we calculated over a period of time). 

Average number of kills per round is 0.679, so if a player had 22 kills in 18 rounds, or 1.22 kills per round, he would have a Kill-Rating of 1.80 (1.22/0.679), meaning he did 80% better than expected on average in the kills department. 

In the same way a Survival-Rating is calculated, as well as a RoundsWithMultipleKills-Rating. These three values are then added together, with Survival-Rating participating with a 0.7 factor (as surviving a round is less important that getting a kill), and then divided by 2.7 to give a 1.0 value for an average performance.

Note: Survived rounds are used instead of deaths, as deaths are reversely proportionate to other stats (having less is better, and more is worse).

What's wrong with K/D ratio?

K/D ratio has several downsides, mainly, it favors players who play fewer rounds and therefore have fewer deaths, giving them high K/D ratios. That is why it isn't really useful for comparing performances from different matches.

For example:

Player 1 had 13-6 (K/D = 2.2) in a match of 18 rounds and Player 2 had 37-17 (K/D = 2.2) in a match of 30 rounds. 

K/D ratio would suggest they had a similar performance, while Player 1 actually had an OK game with 13 kills in 18 rounds, with 4 rounds with 2 kills (2K rounds), and Player 2 had a great game with 37 kills in 30 rounds of a close match with nine 2K rounds, four 3K rounds a one 4K round. If we apply the Rating on the two performances, we get that Player 1 had 1.28, while Player2 had a much higher 1.91.

Another problem can be the fact that K/D ratio doesn't have an actual limit, since it can go from 0 to infinity. That makes it hard to compare performances from a single match as well.  

For example:

Player 1 has 22-4 (K/D = 5.5) in 18 rounds, and in the same match Player 2 has 20-9 (K/D = 2.2). K/D ratio would suggest that Player 1 had a much better game than Player 2, while that wasn't actually the case, as he had only 2 kills more, and 5 deaths less. Rating shows Player 1 had 1.87 and Player 2 had 1.56, suggesting Player 1 had around 20% better performance.

Advantages of Rating

Rating disregards the amount of rounds played in a match, as it considers average values, so it is very useful for comparing performances. It has a mostly limited range, as it can go from 0 to 3 (although rarely over 2, which constitutes an exceptional performance). It also has a well spread range of values that should reflect properly on how many average, good and great performances there are. 

You can see the exact formula for calculating rating on this page.

In the end, just like in any other sport, it is not possible to get an exact evaluation of someone's performance just based on statistics, so of course the rating is not perfect. But, since most people can't watch every match, it can help us better judge and compare players and teams.