Move-order issue in the Grunfeld: ...Nc6-a5 vs ...Nc6-e7

Question

My question relates to certain lines given by Avrukh (2018).

[FEN "..."]   
1. d4 Nf6 2. c4 g6 3. g3 Bg7 4. Bg2 d5 5. cxd5 Nxd5 6. Nf3 Nb6 7. Nc3 Nc6 8. e3 e5 9. d5 

Here 9...Ne7 is the most popular move (88 games in the Chessbase Live database), when Avrukh gives the continuation 10. e4 Bg4 11 h3. Bxf3 12. Qxf3 0-0 13. 0-0.

while 9...Na5 is the second most popular move (22 games in the Chessbase Live database), when Avrukh gives the continuation 10. 0-0 0-0 11 b3.

[FEN "..."]

1. d4 Nf6 2. c4 g6 3. g3 Bg7 4. Bg2 d5 5. cxd5 Nxd5 6. Nf3 Nb6 7. Nc3 Nc6 8. e3 O-O 9. O-O e5 10. d5

10...Na5 is the most popular move (537 games in the Chessbase Live database), when Avrukh gives 11 b3, transposing to a line given under the first diagram.

10...Ne7 is the second most popular move (437 games in the Chessbase Live database), when Avrukh gives 11. e4 Bg4 12. h3 Bxf3 13. Qxf3, transposing to a line given under the first diagram.

Thus according to Avrukh it doesn't matter which move order is chosen.

Given that is the case, why in the top diagram 9...Ne7 is so much more popular than 9...Na5, whereas in the bottom diagram 10...Na5 is somewhat more popular than 10...Ne7?

Avrukh, Boris (2018). Grandmaster Repertoire 2A – King’s Indian and Grünfeld. Quality Chess.

Answer 1

Analyzing this position it seems like the N to the rim has potential issues getting back into the game. W will play b3 and both of the black N's on the Q side are very limited.

After Ne7 the N gets back into the game via c8 and d6 playing an important role blockaiding the p at d5.

That is the best I could find. Transposing to the same position did not come up in my analysis so maybe I am missing something.

Answer 2

There appears to be some additional options to White in the line without castling. I haven't checked a database but perhaps for example, 9...Na5 10.Qd3!? threatening Qb5+ and grabbing the knight on a5. So now if 10...0-0 Black has declared his king and White can consider 11.h4 going for attack.

Answer 3

Eventually I came to suspect that in the top line the ...Nc6-e7 plan (forcing e2-e4) is relatively more popular than ...Nc6-a5 because there is at least one viable line in which a quick ...c7-c6 can be played to hit back at White's centre.

After 8...e5 9 d5 Ne7 10 e4 Black can try 10...c6. White might get an edge following 11 d6 Ng8 but it's complicated. 10...c6 isn't the most popular move in this line, but it's been played by some strong GMs. By contrast, after 8...0-0 9 0-0 e5 10 d5 Ne7 11 e4 then 11...c6 isn't an option as it just loses a piece to 12 d6.

Answer 4

The reason 9...Ne7 is more popular than 9...Na5 is that it gives Black more possibilities than just transposing with castling. I.e.: 9...Ne7 10.e4 c6!? is quite popular in my database, the point being that 11.d6 is answered with 11...Ng8. Note how this wouldn't be possible if Black had castled, since the g8-square wouldn't be vacant.

It may seem odd how the ability to strike immediately with 10...c6 would make 9...Ne7 way more popular than 9...Na5. But consider: why would someone bother playing 8...e5 in the first place (instead of being safer by castling first with 8...0-0) unless he was intending to deviate? If a player is content with the main lines you give, it makes more sense to castle immediately. Being combative with an early 8...e5 implies the player may be looking for an offbeat line, and if this is the case then 9...Ne7 is the natural choice over 9...Na5.