user8291: It seems to me that, although we see lots of Sicilians, especially Najdorfs, Tajmanovs, and Kans, the once popular Scheveningen variation (1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e6 -- or 2...e6 and 5...d6) recently lost a lot of its popularity at top level chess. Nobody seems to play it any more even at club level chess. Is there a clear reason for that?
[FEN ""]    
1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e6


user9477: Style and preferences come and go.
Looking at opening databases this is not a bad variation.
Maybe some 'experts' feel that they get a slightly larger winning % chance with other variations.

user2569: I agree with Joe.  A lot of this is style.  It's pretty solid, and is still played, although often by transposition.  
My guess is that it's a combination of the fact that people favor other variations of the Sicilian and that the Scheveningen is difficult to handle against something as aggressive and the English Attack.  It's also been worked for a couple of decades and its variations are pretty familiar to GMs.    

user4362: As far as I know the theoretical reason for this is the Keres attack. (As stated by Jan Gustafsson in one of many live commentaries.)
[Event "Tata Steel"]
[Site "Wijk aan Zee NED"]
[Date "2013.01.23"]
[EventDate "2013.01.12"]
[Round "10"]
[Result "0-1"]
[White "Pentala Harikrishna"]
[Black "Yifan Hou"]
[ECO "B81"]
[WhiteElo "2698"]
[BlackElo "2603"]
[FEN ""]

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e6 6. g4 h6
7. h4

In fact this line is even entered by white a tempo down, via the h3-Najdorf, so it seems to be just very comfortable for white. 
That being said, Hou Yifan still plays the Scheveningen with black and does so extremely successfully. In fact she won the game from which I took the above opening moves, so white's advantage in the Keres attack is probably nothing that should concern us lesser mortals. 

8291: <p>It seems to me that, although we see lots of Sicilians, especially Najdorfs, Tajmanovs, and Kans, the once popular Scheveningen variation (1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e6 -- or 2...e6 and 5...d6) recently lost a lot of its popularity at top level chess. Nobody seems to play it any more even at club level chess. Is there a clear reason for that?</p>
<pre><code>[FEN &quot;&quot;]    
1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e6
</code></pre>
 9477: <p>Style and preferences come and go.</p>

<p>Looking at opening databases this is not a bad variation.</p>

<p>Maybe some 'experts' feel that they get a slightly larger winning % chance with other variations.</p>
 2569: <p>I agree with Joe.  A lot of this is style.  It's pretty solid, and is still played, although often by transposition.  </p>

<p>My guess is that it's a combination of the fact that people favor other variations of the Sicilian and that the Scheveningen is difficult to handle against something as aggressive and the English Attack.  It's also been worked for a couple of decades and its variations are pretty familiar to GMs.    </p>
 4362: <p>As far as I know the theoretical reason for this is the Keres attack. (As stated by Jan Gustafsson in one of many live commentaries.)</p>

<pre><code>[Event "Tata Steel"]
[Site "Wijk aan Zee NED"]
[Date "2013.01.23"]
[EventDate "2013.01.12"]
[Round "10"]
[Result "0-1"]
[White "Pentala Harikrishna"]
[Black "Yifan Hou"]
[ECO "B81"]
[WhiteElo "2698"]
[BlackElo "2603"]
[FEN ""]

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e6 6. g4 h6
7. h4
</code></pre>

<p>In fact this line is even entered by white a tempo down, via the h3-Najdorf, so it seems to be just very comfortable for white. </p>

<p>That being said, Hou Yifan still plays the Scheveningen with black and does so extremely successfully. In fact <a href="http://www.chessgames.com/perl/chessgame?gid=1705380" rel="noreferrer">she won the game</a> from which I took the above opening moves, so white's advantage in the Keres attack is probably nothing that should concern us lesser mortals. </p>
