10
rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1
[Event "Casual Blitz game"]
[Site "https://lichess.org/GETmjlLj"]
[Date "2021.08.15"]
[White "WMArsyHuda"]
[Black "sicariusnoctis"]
[Result "0-1"]
[UTCDate "2021.08.15"]
[UTCTime "08:40:28"]
[WhiteElo "1622"]
[BlackElo "1874"]
[Variant "Standard"]
[TimeControl "180+2"]
[ECO "B30"]
[Opening "Sicilian Defense: Old Sicilian"]
[Termination "Normal"]
[Annotator "lichess.org"]
[StartPly "33"]

1... c5 2. Nf3 Nc6 { B30 Sicilian Defense: Old Sicilian } 3. Bc4 e6 4. O-O d5 5. exd5 exd5 6. Be2 Nf6 7. d3 Bd6 8. c4 O-O 9. Nc3 d4 10. Ne4 Be7 11. Nfd2 Ne5 12. Nb3 b6 13. a4 a5 14. Bf4 Ng6 15. Bg5 Nxe4 16. Bxe7 Qxe7 17. dxe4 { Stockfish evaluation: -3. }

Analysis board.


Various positional factors include:

  • Black's space advantage.
  • Black's protected passed d pawn.
  • White's knight has no forward moves.
  • White cannot open up the queenside.
  • Black's sole weakness on b6 is difficult to target.
  • Black has ideas such as f5 and Bb7 to target e4.
  • After black opens up the f file, the natural f4 by white is discouraged due to Nxf4.

Factors like these seem solvable (at a minor cost). Indeed, it seems like white can reroute the knight via Nd2, stop Nf4 via g3, and at worst, cover the resulting light-square weaknesses via Bf3-Bg2. Black doesn't have any immediate attack, and apart from his pawn on d4, none of his pieces are encroaching upon white's territory. Optimistically, the d5 square might even be a future outpost. Personally, I would have given such a position a "-1" -- i.e., a slight advantage for black.

What makes this quiet position so positionally dominating for black? How does the accumulation of minor positional advantages make such a large difference here?

6
  • 2
    The e pawn is dropping for white after Bb7 due to the position of the white bishop which can be hassled down the e file and/or from f4 if white ventures f3, after which Black has a huge protected passed pawn on d4 and an extra pawn for no compensation whatsoever.
    – Ian Bush
    Aug 15, 2021 at 9:42
  • Addition to the list: after 17...f5 18.exf5 Bxf5 the white king is weaker than black's king. Later moves like Nf4, Qg5, rooks on f/e-files Bh3 or bishop rerouting to the long diagonal create a lot of threats against the white king. White has problems defending his king mostly because black's pawn structure (especially d4) limits the mobility of white's pieces. The pawns almost like seperate the board into two parts.
    – nyymi
    Aug 15, 2021 at 19:16
  • Your diagram is upside down.
    – bof
    Aug 16, 2021 at 6:12
  • 3
    @bof You could use the "flip" button if you want. Aug 16, 2021 at 11:57
  • @JohnColeman Yes, I know that. But I wondered about OP's peculiar choice to make upside down the default.
    – bof
    Aug 16, 2021 at 21:09

3 Answers 3

10

You mentioned seven points which give Black an advantage. Here are two more:

  • White has a bad bishop, blocked by its own pawns on c4 and e4. Conversely, Black's bishop is good.
  • Black is more ready for kingside play than White. Black is already to move, and his pieces can jump into kingside action faster than White's. For starters, 17...Bb7 connects the rooks with tempo.

Here's a sample line:

[fen "r1b2rk1/4qppp/1p4n1/p1p5/P1PpP3/1N6/1P2BPPP/R2Q1RK1 b - - 0 17"]

1...Bb7 {Black threatens 18...Bxe4 (17...Qxe4? 18.Bf3 results in a skewer). If White allows this, he will be down a pawn, in addition to all the other positional factors.} 2. f3 {This attempt to hold on to material equality does not work, as we will see.} Rae8 {Threatening ...f5, opening lines and making use of Black's superior development (for exf5 see the main line).} 3. Bd3 f5 4. exf5 Nf4 {Threatening ...Qe3+ forking the bishop on d3} 5. Rf2 Qg5 {Now it's ...Nh3+ forking the king and the rook on f2.} 6. Kh1 Re3 {Threatening ...Nxe3. White also needs to keep an eye on shots such as ...Nxg2 Rxg2 Rxf3, with Rf1# ideas if the g2-rook moves.}

It should be obvious that White is in hot water. You write that optimistically the d5-square might even turn into an outpost; as this line shows, Black's position is simply too dynamic, and White will need Black to misplay to even be able to think about subtle positional goals like this.

3
  • Interesting. I first thought Black's Knight would play a bigger role, but this could be a better approach.
    – Mast
    Aug 16, 2021 at 19:49
  • 1
    At the end of your variation, you comment "Threatening ...Nxe3, as well as ...Nxg2 Rxg2 Bxf3." However, I don't think 7...Nxg2 8.Rxg2 Bxf3 to be a threat, because after 9.Qxf3 Rxf3 10.Rxg5 Rxd3 11.Rg3 White keeps an extra knight. The surprising 7...Nxg2 8.Rxg2 Rxf3!? might work better. Anyway, Black's advantage in not in doubt at that point.
    – Evargalo
    Aug 17, 2021 at 16:04
  • @Evargalo good point, I should check these "threats" with an engine =)
    – Allure
    Aug 17, 2021 at 22:25
3

Stepping through the analysis, there are large swings in favour of black on most turns where the white knight on e4 is only protected by the pawn on d3. I'm guessing that Stockfish really likes the passed pawn on the d file.

After the white knight goes to d4 on move 10, Stockfish only thinks that white is okay after its move on move 11 (after the other knight moves to d2 and becomes a second defender of the knight on e4) and on move 14 (when there's a chance to pick up black's undefended knight on e5 in exchange for the knight on e4). As long as white can keep material even without allowing a passed pawn, Stockfish thinks it's okay. On every turn where allowing a passed pawn is the only way to keep material even, Stockfish thinks it's bad for white.

I'm no expert, but that's my guess.

Edit: I'm not sure how to include Stockfish scores in board notation here, so here's a picture.

Lichess running Stockfish 13+ NNUE to a depth of 25

Starting on move 10, Stockfish says that ...Nxe4 is the only dominating move for black, and it is a dominating move only when dxe4 (giving black a passed pawn) is the only way to for white to equalize material.

2

Black is simply better, a pawn up and good pieces.

What makes this quiet position so positionally dominating for black? How does the accumulation of minor positional advantages make such a large difference here?

I think you've committed a common mistake. You've assumed Stockfish evaluation score has anything to do with human evaluations. No, there isn't any direct connection. I could simply scale the scores by a factor of 10, but the engine would still play the same move. The recent introduction of neural network is making the situation even worse.

Trying to break down Stockfish's evaluation on the absolute terms like what you're doing now is ineffective. The scores are here simply to guide Stockfish what to play next.

12
  • 7
    Black is up a pawn? Each side has 7, if I can count.
    – D M
    Aug 15, 2021 at 14:35
  • 2
    Correct me if I am wrong, but my understanding is that Stockfish fish evaluation is based on values of pieces and and lot of positional heuristics, which also evaluated in terms of piece values, so it would be reasonable to expect Stockfish evaluation to reflect human understanding. I think the issue here is that Stockfish has gotten very strong and sees much further, and that is reflected in the evaluation.
    – Akavall
    Aug 15, 2021 at 15:29
  • 5
    Stockfish evaluation does usually reflect human understanding and I think this position is no exception. The higher the evaluation score, the better the position. The position is very dominating for black and that's why the evaluation score is so much in black's favor. I'd say -3 is an evaluation that makes a lot of sense. The question can be given a better answer by explaining positional factors.
    – nyymi
    Aug 15, 2021 at 17:21
  • 2
    @SmallChess It's very well possible that I'm still not understanding you, but now I feel like you haven't addressed the question that Mateen Ulhaq at least means to ask. I think he mostly just wants to understand why the position is very dominating for black even though he himself would evaluate the position as only slightly better for black. That question can be answered by explaining positional factors.
    – nyymi
    Aug 15, 2021 at 17:45
  • 2
    @nyymi OK. I'd approached it from computer chess perspective. An alternative answer is welcome!
    – SmallChess
    Aug 15, 2021 at 17:47

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