Answers.Body: <p>Very interesting question! Why when the Knight was on a4 the engine evaluation was -1 and when the Knight is on c5 the engine evaluation is -5? When the Knight was on a4 Black had an extra pawn, consistent with the engine evaluation of -1. Now that the White Knight is on c5, Black can attack it playing Qe7 followed by Ne4 (attacking the White Queen) and the threat of Qb4 check. So, Black has the opportunity to win some extra tempos and to put the Queen and the Knight in excellent squares.</p>
  <p>White can avoid a check mate with a precise play, but even if that occurs, Stockfish &quot;thinks&quot; that that the endgame is hopeless for White. However, you need to take into consideration that an endgame could be hopeless for an engine, but not for a human. So, -5 is the engine &quot;perspective,&quot; not a human perspective. For example, &quot;my human evaluation would be -2&quot; because Black has an extra pawn, better development, the threat of Ne4 and Qb4 check, and it will be difficult for White to castle. However, many good moves will still be required to win the game. The probability of making mistake exists. We all have seen or played games where Black is winning and suddenly White is winning because Black made a mistake.</p>
  <p>Many years ago, a chess engine evaluation of +1 meant that White was winning with a pawn. For example, in the position that you are asking, many years ago, the engine evaluation would have been -1 because Black has an extra pawn. However, with the availability of $200 computers or $100 cell phones that provide powerful hardware resources, and the creation of modern chess software, chess engines can &quot;see&quot; in seconds 20 half-moves ahead in seconds (10 moves). Also, after those 10 moves chess engines can &quot;guess&quot; black and white chances. So, the engines calification -5 implies that most likely Black will win the game with a high probability (90-100%). If you give the hardware more time, they can &quot;see&quot; 50 and even 60 half-moves (between 25-30 moves).</p>
  <p>When you post this kind of question, the best is that you post either all the moves of the game or the FEN that is a code that allows everybody to paste the position in a chess GUI. In this case, this is the FEN: r2qk2r/ppp2ppp/2n1bn2/2N5/2Bp4/1P2P3/P2Q1PPP/R3K1NR b - - 0 1</p>
  <p>P.S. A half-move is a move of White or Black. A move is a a move of White AND Black.</p>
  <p>P.S.#2 If somebody wants to play the position against the best level of Stockfish on Lichess using Black pieces this is the link: <a href="https://lichess.org/GQ9TqTKa/black" rel="noreferrer">https://lichess.org/GQ9TqTKa/black</a></p>
  <p>P.S.#3 If somebody wants to play the position against the best level of Stockfish on Lichess using White pieces this is the link:
  <a href="https://lichess.org/84aSHZKU" rel="noreferrer">https://lichess.org/84aSHZKU</a></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-12-02T21:05:25.180Z
Answers.Text: I believe OP was asking what the characteristics of the position were that changed the evaluation, not a description of what the evaluation means.
Answers.UserDisplayName: Ross Millikan
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-12-03T02:20:00.060Z
Answers.Text: @RossMillikan I updated my answer to attack on the first and second paragraphs what you suggested. Thank you for the feedback!
Answers.UserDisplayName: Beginner
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-12-03T02:24:37.693Z
Answers.Text: Is there a reason you say the knight used to be on b3? Looks like there's already a pawn there.
Answers.UserDisplayName: D M
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-12-03T02:27:37.750Z
Answers.Text: @DM Thank you! Excellent feedback! It was a mistake. I updated to a4. However, it is just a guess.
Answers.UserDisplayName: Beginner
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-12-03T17:14:24.353Z
Answers.Text: My guess is, the knight was on e3 or a4. I think White didn't like to open up the file where the king is that's why he didn't consider taking the pawn. For me, most natural looking move was to take the pawn (though taking the pawn is kinda risky, depending on the placement of the knight) or bishop. It's really hard to say why the evaluation changed.
Answers.UserDisplayName: Billy Istiak
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-12-03T22:48:07.020Z
Answers.Text: a4 is correct, yes.  My confusion was that chess.com's game review suggested the best next move was Bxc4 and didn't even mention the tactic of playing Qe7.
Answers.UserDisplayName: occipita
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-12-03T23:06:18.790Z
Answers.Text: @occipita Yeah, the chess.com engine suggests to trade bishops and *then* play Qe7. Otherwise White has Nxe6, trading off the attacked piece.
Answers.UserDisplayName: D M
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Answers.CreationDate: 2022-12-02T20:20:59.873Z
Answers.LastActivityDate: 2022-12-03T20:03:49.613Z
Answers.LastEditDate: 2022-12-03T20:03:49.613Z
Answers.UserDisplayName: Beginner
Body: <p>I'm looking at the analysis of a recent daily game I played on chess.com, and have come to this position with black to play.  Chess.com suggests white's last move (Nc5) was a blunder, and the analysis is now down to -5 (it was previously -1, which matches the material difference).  But the suggested line after this (Bxc4 bxc4 - an even exchange of bishops) doesn't come anywhere close to justifying why this move loses 4 points.  What have I missed here?</p>
  <pre><code>[FEN &quot;r2qk2r/ppp2ppp/2n1bn2/2N5/2Bp4/1P2P3/P2Q1PPP/R3K1NR b KQkq - 1 10&quot;]
  </code></pre>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-01T20:07:48.040Z
Comments.Text: Care to give a few more moves of the engine's suggested line?
Comments.UserDisplayName: Ravi Fernando
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-01T21:43:09.713Z
Comments.Text: Where was the knight before it went to c5?
Comments.UserDisplayName: D M
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-01T21:49:44.197Z
Comments.Text: The above comments give good ways to improve the question.
Comments.UserDisplayName: Ross Millikan
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-02T15:43:57.010Z
Comments.Text: 100% tactics; White's main problem is the lack of castling. To make it worse, every Black attacking move is with tempo.
Comments.UserDisplayName: Hauke Reddmann
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-03T22:38:48.397Z
Comments.Text: @RaviFernando - actually, that's all chess.com's game review gives of the suggested line.  I don't know if there's an option I can enable to give more, or if it's because I don't have a premium account, but I often find that I can't get more than a couple of moves out of it.
Comments.UserDisplayName: occipita
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-03T22:39:12.490Z
Comments.Text: @DM - it was on a4.
Comments.UserDisplayName: occipita
Tags: <analysis>
Title: Why is the chess.com analysis of this position -5?
ThreadText: # Why is the chess.com analysis of this position -5?
  
  (Asked by: username_0 on 2022-12-01)
  
  I'm looking at the analysis of a recent daily game I played on chess.com, and have come to this position with black to play.  Chess.com suggests white's last move (Nc5) was a blunder, and the analysis is now down to -5 (it was previously -1, which matches the material difference).  But the suggested line after this (Bxc4 bxc4 - an even exchange of bishops) doesn't come anywhere close to justifying why this move loses 4 points.  What have I missed here?
  [FEN "r2qk2r/ppp2ppp/2n1bn2/2N5/2Bp4/1P2P3/P2Q1PPP/R3K1NR b KQkq - 1 10"]
  
  **Tags:** analysis
  
  > **Comments:**
  > **username_1**: Care to give a few more moves of the engine's suggested line?  
  > **username_2**: Where was the knight before it went to c5?  
  > **username_3**: The above comments give good ways to improve the question.  
  > **username_4**: 100% tactics; White's main problem is the lack of castling. To make it worse, every Black attacking move is with tempo.  
  > **username_0**: @RaviFernando - actually, that's all chess.com's game review gives of the suggested line.  I don't know if there's an option I can enable to give more, or if it's because I don't have a premium account, but I often find that I can't get more than a couple of moves out of it.  
  > **username_0**: @DM - it was on a4.  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_5 on 2022-12-02. Score: 6 | Accepted answer
  
  Very interesting question! Why when the Knight was on a4 the engine evaluation was -1 and when the Knight is on c5 the engine evaluation is -5? When the Knight was on a4 Black had an extra pawn, consistent with the engine evaluation of -1. Now that the White Knight is on c5, Black can attack it playing Qe7 followed by Ne4 (attacking the White Queen) and the threat of Qb4 check. So, Black has the opportunity to win some extra tempos and to put the Queen and the Knight in excellent squares.
  
  White can avoid a check mate with a precise play, but even if that occurs, Stockfish "thinks" that that the endgame is hopeless for White. However, you need to take into consideration that an endgame could be hopeless for an engine, but not for a human. So, -5 is the engine "perspective," not a human perspective. For example, "my human evaluation would be -2" because Black has an extra pawn, better development, the threat of Ne4 and Qb4 check, and it will be difficult for White to castle. However, many good moves will still be required to win the game. The probability of making mistake exists. We all have seen or played games where Black is winning and suddenly White is winning because Black made a mistake.
  
  Many years ago, a chess engine evaluation of +1 meant that White was winning with a pawn. For example, in the position that you are asking, many years ago, the engine evaluation would have been -1 because Black has an extra pawn. However, with the availability of $200 computers or $100 cell phones that provide powerful hardware resources, and the creation of modern chess software, chess engines can "see" in seconds 20 half-moves ahead in seconds (10 moves). Also, after those 10 moves chess engines can "guess" black and white chances. So, the engines calification -5 implies that most likely Black will win the game with a high probability (90-100%). If you give the hardware more time, they can "see" 50 and even 60 half-moves (between 25-30 moves).
  
  When you post this kind of question, the best is that you post either all the moves of the game or the FEN that is a code that allows everybody to paste the position in a chess GUI. In this case, this is the FEN: r2qk2r/ppp2ppp/2n1bn2/2N5/2Bp4/1P2P3/P2Q1PPP/R3K1NR b - - 0 1
  
  P.S. A half-move is a move of White or Black. A move is a a move of White AND Black.
  
  P.S.#2 If somebody wants to play the position against the best level of Stockfish on Lichess using Black pieces this is the link: <https://lichess.org/GQ9TqTKa/black>
  
  P.S.#3 If somebody wants to play the position against the best level of Stockfish on Lichess using White pieces this is the link:
  <https://lichess.org/84aSHZKU>
  
  > **Comments:**
  > **username_3**: I believe OP was asking what the characteristics of the position were that changed the evaluation, not a description of what the evaluation means.  
  > **username_5**: @RossMillikan I updated my answer to attack on the first and second paragraphs what you suggested. Thank you for the feedback!  
  > **username_2**: Is there a reason you say the knight used to be on b3? Looks like there's already a pawn there.  
  > **username_5**: @DM Thank you! Excellent feedback! It was a mistake. I updated to a4. However, it is just a guess.  
  > **username_6**: My guess is, the knight was on e3 or a4. I think White didn't like to open up the file where the king is that's why he didn't consider taking the pawn. For me, most natural looking move was to take the pawn (though taking the pawn is kinda risky, depending on the placement of the knight) or bishop. It's really hard to say why the evaluation changed.  
  > **username_0**: a4 is correct, yes.  My confusion was that chess.com's game review suggested the best next move was Bxc4 and didn't even mention the tactic of playing Qe7.  
  > **username_2**: @username_0 Yeah, the chess.com engine suggests to trade bishops and *then* play Qe7. Otherwise White has Nxe6, trading off the attacked piece.  
  
  ---
  
  