In 1970, FIDE adopted Elo's system for rating current players. So, one way to compare players of different eras is to compare their Elo ratings. The best-ever Elo ratings are tabulated below,.
The average Elo rating of top players has risen over time. For instance, the average of the top 100 has risen from 2645 in July 2001 to 2665 in July 2006. Many people believe that this rise is mostly due to a system artifact known as ratings inflation, making it impractical to compare players of different eras.
Elo was of the opinion that it was futile to attempt to use ratings to compare players from different eras; in his view, they could only possibly measure the strength of a player as compared to his or her contemporaries. He also stated that the process of rating players was in any case rather approximate; he compared it to "the measurement of the position of a cork bobbing up and down on the surface of agitated water with a yard stick tied to a rope and which is swaying in the wind".
One caveat is that a Chessmetrics rating takes into account the frequency of play. According to Sonas, "As soon as you go a month without playing, your Chessmetrics rating will start to drop". While it may be in the best interest of the fans for chess-players to remain active, it is not clear why a person's rating, which reflects his/her skill at chess, should drop if the player is inactive for a period of time.
Sonas, like Elo, acknowledges that it is useless to try to compare the strength of players from different eras. In his explanation of the Chessmetrics system, he says:
Nevertheless Sonas' Web site does compare players from different eras, and shows that in such cases the Chessmetrics system is rather sensitive to the length of the periods being compared, for example in spring 2008 its rankings were:
|Position||1 year||5 years||10 years||15 years||20 years|
|1||Bobby Fischer||Garry Kasparov||Garry Kasparov||Garry Kasparov||Garry Kasparov|
|2||Garry Kasparov||Emanuel Lasker||Emanuel Lasker||Anatoly Karpov||Anatoly Karpov|
|3||Mikhail Botvinnik||José Capablanca||Anatoly Karpov||Emanuel Lasker||Emanuel Lasker|
|4||José Capablanca||Mikhail Botvinnik||José Capablanca||José Capablanca||Alexander Alekhine|
|5||Emanuel Lasker||Bobby Fischer||Bobby Fischer||Alexander Alekhine||Viktor Korchnoi|
|6||Alexander Alekhine||Anatoly Karpov||Mikhail Botvinnik||Mikhail Botvinnik||Vassily Smyslov|
In a 2005 ChessBase article, Sonas uses Chessmetrics to evaluate historical annual performance ratings and comes to the conclusion that Kasparov was dominant for the most number of years, followed closely by Lasker and Karpov.
The "Classical" World Chess Championship matches were analyzed, and the results for the fourteen Classical World Champions were presented.
Players with fewest average errors:
The method received a number of criticisms, including: the study used a modified version of Crafty rather than the standard version; even the standard version of Crafty was not strong enough to evaluate the world champions' play; one of the modifications restricted the search depth to 12 half-moves, which is often insufficient. As of 2006 Crafty's ELO rating was 2657, below many historical top human players and several other computer programs.
|Champion||Total||Undisputed||FIDE||Classical||Years as champion|
|José Raúl Capablanca||1||1||6|