user24016: In the following position, Stockfish 14 says the move 1...Be6 is weak, with the score going from -0.4 to +0.7.
[Title "Black to move"]
[FEN "r1b1kb1r/p4ppp/2p5/1p2P3/8/1BP5/P4PPP/R1BK3R b kq - 1 12"]

1...Be6 2.Bxe6 fxe6

What's wrong with it? 1...Be6 2.Bxe6 fxe6  and White's e-pawn is now fixed, and it's fixed on a dark square, the same color as the remaining Bishops.

user15049: What's wrong with it? 1...Be6 2.Bxe6 fxe6?
Probably nothing. At the end of your line white has slightly more active rooks and some space advantage, but the fact that black's pawns are on better squares and his queen side majority will give black good counterplay.
Stockfish wants to move the Bc8 to a6 in his preferred line 1...a5 2.a4 b4 3.cxb4 Bxb4. The bishops then support the c-pawn, but this will lead to nothing against sensible defense.
Both moves can be analyzed to 0.00, so in absolute terms, Stockfish tells wonderful stories.

24016: <p>In the following position, Stockfish 14 says the move <strong>1...Be6</strong> is weak, with the score going from -0.4 to +0.7.</p>
<pre><code>[Title &quot;Black to move&quot;]
[FEN &quot;r1b1kb1r/p4ppp/2p5/1p2P3/8/1BP5/P4PPP/R1BK3R b kq - 1 12&quot;]

1...Be6 2.Bxe6 fxe6
</code></pre>
<p>What's wrong with it? <strong>1...Be6 2.Bxe6 fxe6</strong>  and White's e-pawn is now fixed, and it's fixed on a dark square, the same color as the remaining Bishops.</p>
 15049: <p><em>What's wrong with it? 1...Be6 2.Bxe6 fxe6?</em></p>
<p>Probably nothing. At the end of your line white has slightly more active rooks and some space advantage, but the fact that black's pawns are on better squares and his queen side majority will give black good counterplay.</p>
<p>Stockfish wants to move the Bc8 to a6 in his preferred line 1...a5 2.a4 b4 3.cxb4 Bxb4. The bishops then support the c-pawn, but this will lead to nothing against sensible defense.</p>
<p>Both moves can be analyzed to 0.00, so in absolute terms, Stockfish tells wonderful stories.</p>
