Answers.Body: <p>White is a piece down for just a pawn in this position. Taking the rook would give them a reasonably balanced position, but by refusing to take they get a totally lost one.</p>
  <p>There are also some ideas with Bg4 and Nd4 that speculate with trapping the queen or taking on c2 (potentially forking the rook and queen if she moves to the wrong square).</p>
  <p>I wouldn't pay too much attention to the specific number. Whether it's -3 or -7 it doesn't matter much. The fact is that White should have taken the rook and any other move is a blunder.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-12-25T20:36:03.917Z
Answers.Text: Another detail coming out bad for White: The knight g5 can't safely retreat, on f3 it will be pinned (the Q only has d1 as safe field) and on h3 exchanged. Thus White, in addition to material woes, also has a trashed castling position.
Answers.UserDisplayName: Hauke Reddmann
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Answers.CreationDate: 2022-12-25T12:19:22.547Z
Answers.LastActivityDate: 2022-12-25T12:19:22.547Z
Answers.UserDisplayName: David
Answers.Body: <p>It seems like white played Bxf7, and after Rxf7, instead of taking the rook with Nxf7, white played Qf3. Now black -among others- can play the simple Rf8 and are a piece up for a pawn.</p>
  <p>The fact that the advantage is so large just depends on the engine and its version. For example, from Stockfish 15.1 evaluations are not that extreme (in my laptop it's &quot;only&quot; -5).</p>
  <p>In any case, white position goes from -1 to completely lost not because Qf3 puts the queen in danger or anything like that, but just because they didn't play Nxf7 (winning a rook for a knight), sort of balancing the material on the board.</p>
  
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Answers.CreationDate: 2022-12-25T18:50:20.390Z
Answers.LastActivityDate: 2022-12-26T00:39:12.323Z
Answers.LastEditDate: 2022-12-26T00:39:12.323Z
Answers.UserDisplayName: emdio
Body: <pre><code>[FEN &quot;&quot;]
  [startply &quot;16&quot;]
  [StartFlipped &quot;1&quot;]
  
  1. e4 d6 2. Bc4 Nf6 3. Nc3 g6 4. d3 Bg7 5. Nf3 Nc6 6. O-O e5 7. Ng5 O-O 8. Bxf7+ Rxf7 9. Qf3
  </code></pre>
  <p>Why does the engine go from -1.5 to -8.5 after the queen move? There isn't an opportunity to trap the queen yet and the black is only two points ahead in material. My guess is that the queen walks into a discovered attack by the rook and the queen can be immediately attacked with Nd4. I played Rf8 afterwards to keep my rook on the f file. The top engine line is just to move the queen back to where it came from and then the knight is kicked out too.</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T02:37:58.447Z
Comments.Text: Why didn't you take the rook? And It's losing for Nd4 and Bg4.
Comments.UserDisplayName: Billy Istiak
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T02:40:17.920Z
Comments.Text: @BillyIstiak I played as black (idk how to flip the PGN) I don't know why White didn't take back
Comments.UserDisplayName: qwr
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T13:06:47.087Z
Comments.Text: @qwr What engine at what depth is returning -8.5? I'm not getting that unless I run it at, like, depth 3.
Comments.UserDisplayName: D M
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T13:48:41.393Z
Comments.Text: *black is only two points ahead in material* Engines are waaaay past the time when their evaluations reflected the material on the board. Plus, these days most engines index their evaluations to chance of victory.
Comments.UserDisplayName: Allure
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T13:51:30.313Z
Comments.Text: @DM lichess's stockfish 14+ NNUE at depth 26 https://lichess.org/analysis/standard/r1bq2k1/ppp2rbp/2np1np1/4p1N1/4P3/2NP1Q2/PPP2PPP/R1B2RK1_b_-_-_1_9
Comments.UserDisplayName: qwr
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T13:52:13.690Z
Comments.Text: @Allure I've found Stockfish will report somewhat more than material imbalance when the position is otherwise equal. So a blundered bishop or knight will report say -5.
Comments.UserDisplayName: qwr
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T14:01:46.387Z
Comments.Text: @qwr Stockfish no longer uses material imbalance. +1 is not the same as "extra pawn with no compensation". +1 now means Stockfish thinks White has a 50% chance of winning. See https://github.com/official-stockfish/Stockfish/commit/758f9c9350abee36a5865ec701560db8ea62004d.
Comments.UserDisplayName: Allure
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T14:07:00.383Z
Comments.Text: @Allure the engine I used is SF14 NNUE
Comments.UserDisplayName: qwr
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T14:07:08.593Z
Comments.Text: @Allure That's good to know, but that's in the notes for version 15.1, which is a higher version that what was used here, so it probably wouldn't apply here.
Comments.UserDisplayName: D M
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T14:27:40.890Z
Comments.Text: @DM it still applies, because ever since NNUE Stockfish's evaluation (usually, outside of the few positions that use classical eval) depends on win percentage, and Stockfish adopted NNUE in version 12.
Comments.UserDisplayName: Allure
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T15:14:23.090Z
Comments.Text: @Allure Stockfish used to think it did, according to an old answer of mine, although my source seems to have disappeared. https://chess.stackexchange.com/questions/17196/how-are-the-scores-decided-in-chess-correct/17204#17204
Comments.UserDisplayName: D M
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-25T16:16:51.970Z
Comments.Text: @allure I just remembered that the wayback machine is a thing. https://web.archive.org/web/20180424122041/http://support.stockfishchess.org/discussions/questions/1303-stockfish-evaluation-numbers-and-their-meaning
Comments.UserDisplayName: D M
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-12-26T10:36:05.967Z
Comments.Text: @DM I take back what I wrote - it seems during the HCE era, Stockfish evals indeed were indexed by the value of a pawn, although they used the endgame value of pawns and not the middlegame one.
Comments.UserDisplayName: Allure
Tags: <engines><analysis>
Title: Why is Qf3 losing in this position?
ThreadText: # Why is Qf3 losing in this position?
  
  (Asked by: username_0 on 2022-12-25)
  
  [FEN ""]
  [startply "16"]
  [StartFlipped "1"]
  
  1. e4 d6 2. Bc4 Nf6 3. Nc3 g6 4. d3 Bg7 5. Nf3 Nc6 6. O-O e5 7. Ng5 O-O 8. Bxf7+ Rxf7 9. Qf3
  
  Why does the engine go from -1.5 to -8.5 after the queen move? There isn't an opportunity to trap the queen yet and the black is only two points ahead in material. My guess is that the queen walks into a discovered attack by the rook and the queen can be immediately attacked with Nd4. I played Rf8 afterwards to keep my rook on the f file. The top engine line is just to move the queen back to where it came from and then the knight is kicked out too.
  
  **Tags:** engines, analysis
  
  > **Comments:**
  > **username_1**: Why didn't you take the rook? And It's losing for Nd4 and Bg4.  
  > **username_0**: @BillyIstiak I played as black (idk how to flip the PGN) I don't know why White didn't take back  
  > **username_2**: @username_0 What engine at what depth is returning -8.5? I'm not getting that unless I run it at, like, depth 3.  
  > **username_3**: *black is only two points ahead in material* Engines are waaaay past the time when their evaluations reflected the material on the board. Plus, these days most engines index their evaluations to chance of victory.  
  > **username_0**: @DM lichess's stockfish 14+ NNUE at depth 26 https://lichess.org/analysis/standard/r1bq2k1/ppp2rbp/2np1np1/4p1N1/4P3/2NP1Q2/PPP2PPP/R1B2RK1_b_-_-_1_9  
  > **username_0**: @username_3 I've found Stockfish will report somewhat more than material imbalance when the position is otherwise equal. So a blundered bishop or knight will report say -5.  
  > **username_3**: @username_0 Stockfish no longer uses material imbalance. +1 is not the same as "extra pawn with no compensation". +1 now means Stockfish thinks White has a 50% chance of winning. See https://github.com/official-stockfish/Stockfish/commit/758f9c9350abee36a5865ec701560db8ea62004d.  
  > **username_0**: @username_3 the engine I used is SF14 NNUE  
  > **username_2**: @username_3 That's good to know, but that's in the notes for version 15.1, which is a higher version that what was used here, so it probably wouldn't apply here.  
  > **username_3**: @DM it still applies, because ever since NNUE Stockfish's evaluation (usually, outside of the few positions that use classical eval) depends on win percentage, and Stockfish adopted NNUE in version 12.  
  > **username_2**: @username_3 Stockfish used to think it did, according to an old answer of mine, although my source seems to have disappeared. https://chess.stackexchange.com/questions/17196/how-are-the-scores-decided-in-chess-correct/17204#17204  
  > **username_2**: @allure I just remembered that the wayback machine is a thing. https://web.archive.org/web/20180424122041/http://support.stockfishchess.org/discussions/questions/1303-stockfish-evaluation-numbers-and-their-meaning  
  > **username_3**: @DM I take back what I wrote - it seems during the HCE era, Stockfish evals indeed were indexed by the value of a pawn, although they used the endgame value of pawns and not the middlegame one.  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_4 on 2022-12-25. Score: 9
  
  White is a piece down for just a pawn in this position. Taking the rook would give them a reasonably balanced position, but by refusing to take they get a totally lost one.
  
  There are also some ideas with Bg4 and Nd4 that speculate with trapping the queen or taking on c2 (potentially forking the rook and queen if she moves to the wrong square).
  
  I wouldn't pay too much attention to the specific number. Whether it's -3 or -7 it doesn't matter much. The fact is that White should have taken the rook and any other move is a blunder.
  
  > **Comments:**
  > **username_5**: Another detail coming out bad for White: The knight g5 can't safely retreat, on f3 it will be pinned (the Q only has d1 as safe field) and on h3 exchanged. Thus White, in addition to material woes, also has a trashed castling position.  
  
  ---
  
  ### Answer by username_6 on 2022-12-25. Score: 5
  
  It seems like white played Bxf7, and after Rxf7, instead of taking the rook with Nxf7, white played Qf3. Now black -among others- can play the simple Rf8 and are a piece up for a pawn.
  
  The fact that the advantage is so large just depends on the engine and its version. For example, from Stockfish 15.1 evaluations are not that extreme (in my laptop it's "only" -5).
  
  In any case, white position goes from -1 to completely lost not because Qf3 puts the queen in danger or anything like that, but just because they didn't play Nxf7 (winning a rook for a knight), sort of balancing the material on the board.
  
  
  ---
  
  