"You cannot expect the Na5 move to play the same role in both lines."
That is all fine and dandy. I just want to know why not Na5. Let's look at a higher rated game. These guys have a rating of ~2400 on another server. It's probably not enough to make them a full fledged FIDE IM, but they are miles ahead of me. Closer to you perhaps. Black played the following. This leads me to believe c5 might be the missing ingredient.
Yes, if you check my post #14 you will find "His c7-Pawn will advance to c5 to pressure the d4-Pawn"... this comment was made in reference to the Yates (White's d4 without h3) variation.
It's worth noting that the Breyer variation used to be very popular (Spassky for example was an adherent) and it avoids the whole Na5 question by moving it back to b8 instead!
Black loses time by retreating the Knight back to its original square on b8, but in return he gets a fluid, natural development... with his LSB going to b7, his f8-Rook to e8 (pressuring the White e-Pawn), his c7-Pawn cleared to advance to c5 whenever the time seems right, his DSB redeploying to g7 (after Bf8 and g7-g6). All this without that stray Knight out of play on a5... it finds a useful role on d7 instead.
Yes, if you check my post #14 you will find "His c7-Pawn will advance to c5 to pressure the d4-Pawn"... this comment was made in reference to the Yates (White's d4 without h3) variation
The way it was worded gave me the impression that you should play Bg4-Bh5-Bg6 exerting pressure on the e4 square first, then play c5 to pressure the d4 pawn.
Are you making this distinction? Are you saying it could happen in either order? Are you saying that only one way should be decided?
It's hard to see the sequence of the moves if you aren't just listing a grocery list of moves to make.
The Bishop on g6 exerts pressure on the e4-Pawn.
Since Black is playing exd4 (opening the e-file), his Rook can later come to e8 to reinforce that pressure.
His c7-Pawn will advance to c5 to pressure the d4-Pawn,
and after (THIS LEADS ME TO BELIEVE YOU WERE TELLING ME WHAT ORDER THE MOVES SHOULD BE PLAYED IN) N(f6)-d7 his e7-Bishop can play to f6, both reinforcing the attack on d4 and also clearing the e-file for the e8-Rook to cooperate with the g6-Bishop against the e4 square.
The theme is converging pressure on White's e4/d4 Pawn duo.
It seems like you are not claiming an order of moves now. Is this true?
I was commenting on the specific line that you were asking about... but c7-c5 is a VERY common theme in the Ruy Lopez, and not only in the Yates variation. It also occurs in the Chigorin, the Breyer, the Keres, and other lines.
Check my edit in post #23 above, by the way.
I think one key idea you can take away from this discussion is the idea that you often attack a pawn--or square--by first attacking its defenders. In the variation after 9.d4, 9...Bg4 is an attack on the d4 pawn. Your question "How do you attack a dark-square pawn with a light-squared bishop?" is very reasonable, but now you know: you are attacking the defender of the dark square. This is an idea you can use.
Different lines are NOT just different sequences of moves. They also embody different IDEAS.
In the Chigorin variation, White concedes a tempo (playing 9. h3 before Black's LSB has even moved) in order to limit Black's active counter-play against White's Pawn center. In reply, Black digs in and fortifies his foothold in the center (hanging on stubbornly to the e5 Pawn) and tries to generate his active counterplay on the Queen's side.
In the Yates variation, White saves a move by omitting a precautionary 9. h3 and playing d2-d4 directly... only playing h3 in reply to a Bg4 move, so no tempo is lost. Black counters by TRADING AWAY his e5-Pawn (totally different from his strategy in the Chigorin) and using the open e-file and the Bg4 sortie to organize direct pressure on White's Pawn center. He looks for counterplay more in the center than on the flank.
- Note that I'm just describing typical plans. Side-lines exist in both variations. -
These two situations are not just different... they are nearly 180 degrees opposed to each other... fanatically strongpointing the e5 Pawn (Chigorin) vs happily trading it off (Yates). You cannot expect the Na5 move to play the same role in both lines.