Unusual sequence of opening moves in the Open Ruy Lopez with 6.d4 Be7 As title above,could someone kindly explain the tactical highlights of the rather unusual sequence of moves arising with the recent interpretation of the Open Ruy Lopez with 6.d4 Be7?
[FEN &quot;&quot;]
1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O Nxe4 6.d4 Be7 7.Re1 b5 8.Rxe4 d5 9.Nxe5 Nxe5 10.Rxe5 bxa4

For example, why isn't White simply retreating the Bishop to b3 with 8.Bb3 ? Why 9.Nxe5 instead of simply retreating the Rook with, for example, 9.Re1 ? Why isn't Black taking the Rook with 9...dxe4 ? And so on.
I think the first step is to look at the analysis of the first 9 to 10 moves;
It is all pretty standard for the first few moves.

e4 e5 2. Nf3 Nc6
Bb5 a6 4. Ba4 Nf6
O-O Nxe4 6. d4 Be7
Re1 b5
Rxe4 {[#] And now Bb3 would win. C84: Closed Ruy Lopez: Unusual White 6th moves.} d5
Nxe5 Nxe5
Rxe5 {Threatens to win with Bb3. White is better.} bxa4

So looking at the logical developments;
   [FEN &quot;&quot;]
   1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Nxe4 6. d4 Be7 7. Re1 b5 8. Rxe4 d5 9. Nxe5 Nxe5 10. Rxe5 bxa4 11. Qe2 c6 12. Bd2 Be6 13. f4 g6 14. Nc3 a3 15. b3 Bd6 16. f5 gxf5 *

11. Qe2 {Adds an extra defender to the e5 rook. Provides a potential battery into blacks territory on the open e-file.} c6 {adds a defender to the isolated d5 pawn.}
12. Bd2 {Unable to develop to g5to target the e7 bishop. Black can easily counter with f6 bother attacking and defending. Idea to develop to Bb4} Be6 {Adds and extra barrier to whites e5 rook and e2 queen. provides additional support for central pawns as well as being supported / supporting the f7 pawn.  This also unpins Be7 which has good
attack opportunities on f6 primarily.}
13. f4 {Adds an additional defender. Can be pushed to harrass Be6} g6
14. Nc3 {Try to capture some lazy material on a4} a3 {White can capture but doesn't want to open up the b file or stack pawns on the a file}
15. b3 Bd6 {Blacks bishop finally back in the game. Threatens capture of the e5 rook}
16. f5 {Stalling move. If black plays Bxe5 white can capture fxe6 which forces black to respond fxe6 followed by Qxd5. Material is largely even} gxf5 *
End Result:
Positions are equal , arguable that white has minor advantage. Considering white had a slightly better position at move 10, and is only down a pawn I believe. Is an interesting
Some Master Games from this position
First Notable game I can see in my Database.
Lasker vs Tarrasch (1916) - https://www.chess.com/games/view/15756559 : In fact theres two games with this exact position from the same year.
More Recent Games;
Caruana vs Carlsen (2018) - https://www.chess.com/games/view/15606031
Nakamura vs Caruana (2019) - https://www.chess.com/games/view/15656519