Even at highest levels players make significant, but human, mistakes. On the other hand there exists a great amount of opening theory, with lines studied in depth, especially the mainlines. Isn't the precision of theory evaluation and human imprecision in contradiction? Is it generally difficult to punish small opening sins even at the highest (human) level (Evans-Gambit, Cozio defense, 1. ... a6)? If so, is the fact that most advanced players learn and play some kind of mainlines just some kind of gentlemen's agreement? Or do they score significantly better?

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    Personal opinion: Definitely not, I have FM strength but no specific (variant) knowledge about any opening...and always am on the fritz after ten moves. Stockfish/Lichess says +0.2 after 1.e4 a6, add 2.d4 b5 for +0.6 and still a 50/50 in game statistics, so this is hardly a convincing example for your vast generalization. (Also: opinion-prone question, try to reformulate, e.g.: do main lines score significantly better?) Jul 21, 2021 at 18:58
  • Thank you for your answer, I'll try to reformulate it in the way you mentioned. 1. ... a6 should just be an example, but of course an extreme one. I've could also choosen Evans-Gambit or the Cozio-Defense. Jul 21, 2021 at 20:08
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    @HaukeReddmann what database shows you 50/50? When I enter 1.e4 a6 in the lichess masters database, White scores 60% instead of the usual 54%. After 2.d4 b5 the score goes up further to 62%. That is a significant difference. That being said, "bad" variations can still score ok if they are relatively unknown, since then many players might not know how to punish them.
    – koedem
    Jul 22, 2021 at 0:05
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    Or rather, which database I meant. Maybe you mean the database for all games played on lichess? That indeed looks much more even, although I interpreted the question as whether it scores significantly better for strong players (and presumably in long games).
    – koedem
    Jul 22, 2021 at 0:22
  • @koedem: Indeed, I just went on the Lichess analysis page. (And also indeed, biases introduced by player strengths must be taken in account first before one can give a valid answer.) Jul 22, 2021 at 6:53

1 Answer 1


The score of openings is more often a combination of the strength of players which play it, the situations in which the openings are played, and of course the objective merit of the opening. Looking at the database you will often see sidelines which have much higher scores than mainlines, often these are trendy lines which are played by players who are up to date on theory and playing for a win against weaker opponents. That doesn't mean these lines are objectively better than main lines, most of the time main lines follow a traditional ~51% type of score, as strong players are often choosing them when playing to be solid.

For a specific example lets consider the Nimzo-Indian: 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4. Here the three most popular moves 4.e3,Qc2,Nf3 all score around 52% (megabase), the sharp and trendy 4.f3 scores 53.5% and the old line 4.a3 scores a miserable 46%. These are all main lines and the only conclusion I would infer from these numbers is that strong players are playing 4.f3 for a win against weaker players. While black players in general find it easiest to win against 4.a3. If I was playing a player rated 400 points below me I would be much more tempted to play 4.f3 as I know the chances of them making a mistake is much higher than me making a mistake. However if I was playing a player 400 points above me, I would rather play a safer move like 4.Qc2, as there even if I make some small mistakes it will be easier to hold a draw.

To refer to the first part of your question, I am certain that all of these 4th moves in the Nimzo-Indian contain long theoretical lines which end in drawish positions. In a practical game between human players however it is more important who has a better understanding of the position, and luring your opponent into a position which you understand better than they do is one of the main goals of the opening. So in the end the score of an opening is largely irrelevant. Main lines are fundamentally sound positions which often afford players to make small mistakes without serious deteriation of the position.

  • Interesting theories. Another case to investigate: after 1. e4 e6 2. Qe2, 2 ... c5 is about 8 times as prevalent as 2 ... Be7 in 365chess.com's database of master games, but Be7 has a much higher black win %age and lower white win %age. Why? Because Black plays Be7 only against lower-rated players? (It doesn't look like a trap to me.)
    – Rosie F
    Nov 16, 2021 at 14:20
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    Good question about 2.Qe2, I would say that Qe2 is quite a rare move and that if White is playing that then usually they desperate to mix things up away from a mainline anyway. The sample size is quite small with around 1000 games in my database for 2...Be7 so I would put the variations down to random fluctuations. Many continuations look decent for Black after 2.Qe2 and I don't think Black is required to know much theory to play the position. I would say that strong Black players may be encouraged to avoid 2...c5 as it transposes to KIA main lines which the White player may be familiar with. Nov 16, 2021 at 15:25

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