Answers.Body: <p>Computers have a different idea of what the word &quot;blunder&quot; means than a human. To a computer a blunder is any move that changes the evaluation of the position in a bad way more than a pawn's worth, even if the reason is not obvious. To a human, a blunder is an obviously bad move.</p>
  <p>So, your move is not really a blunder, it's just a missed opportunity. By playing Nd4 instead of d4, you would be threatening 13...a6 14. Ba4 b5 winning the bishop which is trapped. There is no way for White to escape this because if plays 13. b4 to try to make a luft for the bishop, then Black just plays 13...cxb4 and the White knight is under attack. If the knight moves, then the bishop is lost because the knight on d4 is attacking it.</p>
  <p>This position is a good example of why you want to get your pieces out of attack and put pressure on the enemy pieces. Nd4! does both. It removes the knight from the bishop's attack and makes an attack of its own, two things at once.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-04-10T12:17:09.660Z
Answers.LastActivityDate: 2021-04-10T12:17:09.660Z
Answers.UserDisplayName: Cecil De Vere
Answers.Body: <p>because white plays Na4 and attacks the pawn at c5. Impossible to secure with b4 because the Knight will be lost after that.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-04-09T14:38:49.657Z
Answers.LastActivityDate: 2021-04-09T14:38:49.657Z
Answers.UserDisplayName: ChessPlayer
Body: <p>I recently played a game featuring the Old Sicilian with a bit of a branch-off. White played 3. Bc4 after 2. Nf3 Nc6, which I don't deal well with. I ended up playing 12... d4, attacking the White knight, which the analysis later marked as a blunder. I'm not an advanced chess player, and I can't find out why this would be so.</p>
  <pre><code>[FEN &quot;&quot;]
  [startply &quot;23&quot;]
  
  1. e4 c5 2. Nf3 Nc6 3. Bc4 d6 4. O-O Nf6 5. d3 g6 6. Nc3 Bg7 7. b3 O-O 8. Bb2 Bg4 9. h3 Bxf3 10. gxf3 e6 11. f4 d5 12. Bb5 d4 13. Bxc6 dxc3 14. Bxb7 cxb2 15. Rb1 Rb8 16. Ba6 Nh5 17. Rxb2 Nxf4 18. Qf3 Qg5+ 19. Kh1 Bxb2 20. Rg1 Qe5 21. Rb1 Ba3 22. Qg3 c4 23. dxc4 Bd6 24. a3 Rb6 25. Bb5 Bxa3 26. Ra1 Bd6 27. Rxa7 Ne2 28. Qe3 Qh2#
  </code></pre>
  <p>Can anybody please can clue me in to how 12... d4 was a blunder?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-04-09T02:46:22.460Z
Comments.Text: Right, we'd rather have the PGN (or at least the FEN of the position in question.) The graphic goes by too fast.
Comments.UserDisplayName: D M
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-04-09T03:14:45.727Z
Comments.Text: Thanks. I'll add it in a second...
Comments.UserDisplayName: randomlurker
Tags: <analysis><middlegame>
Title: Why is 12... d4 a blunder?
ThreadText: # Why is 12... d4 a blunder?
  
  (Asked by: username_0 on 2021-04-09)
  
  I recently played a game featuring the Old Sicilian with a bit of a branch-off. White played 3. Bc4 after 2. Nf3 Nc6, which I don't deal well with. I ended up playing 12... d4, attacking the White knight, which the analysis later marked as a blunder. I'm not an advanced chess player, and I can't find out why this would be so.
  [FEN ""]
  [startply "23"]
  
  1. e4 c5 2. Nf3 Nc6 3. Bc4 d6 4. O-O Nf6 5. d3 g6 6. Nc3 Bg7 7. b3 O-O 8. Bb2 Bg4 9. h3 Bxf3 10. gxf3 e6 11. f4 d5 12. Bb5 d4 13. Bxc6 dxc3 14. Bxb7 cxb2 15. Rb1 Rb8 16. Ba6 Nh5 17. Rxb2 Nxf4 18. Qf3 Qg5+ 19. Kh1 Bxb2 20. Rg1 Qe5 21. Rb1 Ba3 22. Qg3 c4 23. dxc4 Bd6 24. a3 Rb6 25. Bb5 Bxa3 26. Ra1 Bd6 27. Rxa7 Ne2 28. Qe3 Qh2#
  
  Can anybody please can clue me in to how 12... d4 was a blunder?
  
  **Tags:** analysis, middlegame
  
  > **Comments:**
  > **username_1**: Right, we'd rather have the PGN (or at least the FEN of the position in question.) The graphic goes by too fast.  
  > **username_0**: Thanks. I'll add it in a second...  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_2 on 2021-04-10. Score: 1
  
  Computers have a different idea of what the word "blunder" means than a human. To a computer a blunder is any move that changes the evaluation of the position in a bad way more than a pawn's worth, even if the reason is not obvious. To a human, a blunder is an obviously bad move.
  
  So, your move is not really a blunder, it's just a missed opportunity. By playing Nd4 instead of d4, you would be threatening 13...a6 14. Ba4 b5 winning the bishop which is trapped. There is no way for White to escape this because if plays 13. b4 to try to make a luft for the bishop, then Black just plays 13...cxb4 and the White knight is under attack. If the knight moves, then the bishop is lost because the knight on d4 is attacking it.
  
  This position is a good example of why you want to get your pieces out of attack and put pressure on the enemy pieces. Nd4! does both. It removes the knight from the bishop's attack and makes an attack of its own, two things at once.
  
  
  ---
  
  ### Answer by username_3 on 2021-04-09. Score: 0
  
  because white plays Na4 and attacks the pawn at c5. Impossible to secure with b4 because the Knight will be lost after that.
  
  
  ---
  
  