Black here has very natural development - his bishop is controlling d5, his knight is ready to jump to d4 (thus interfering with white heavy pieces control of d-file). Because of this he can liquidate into drawn (if difficult due to worse pawn structure) ending after 11. O-O-O Nd4 12. Nxd4 exd4 13. Nd5 Bxd5 14. exd5
This way of playing with Bg5 is not so popular anymore today (Be3 is way more topical, with either O-O or O-O-O), but it offers clearest comparison to analogous position.
Black needs to control d5 and e6 is off-limits, so he has to reroute his bishop to c6, where his knight wants to be. White has lasting pressure on d-file, it's not clear how black will develop his knight and he cannot easily force pieces off the board.
Compare positions you get after:
- 1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Be2 e5 7. Nb3 Be7 8. Bg5 Be6 9. Bxf6 Bxf6 10. Qd3 Nc6
Black here has very natural development - his bishop is controlling d5, his knight is ready to jump to d4 (thus interfering with white heavy pieces control of d-file). Because of this he can liquidate into drawn (if difficult due to worse pawn structure) ending after 11. O-O-O Nd4 12. Nxd4 exd4 13. Nd5 Bxd5 14. exd5
This way of playing with Bg5 is not so popular anymore today (Be3 is way more topical, with either O-O or O-O-O), but it offers clearest comparison to analogous position.
- 1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Be2 e5 7. Nb3 Be6 8. f4 Be7 9. f5 Bd7 10. Bg5 Bc6 11. Bxf6 Bxf6 12. Qd3
Black needs to control d5 and e6 is off-limits, so he has to reroute his bishop to c6, where his knight wants to be. White has lasting pressure on d-file, it's not clear how black will develop his knight and he cannot easily force pieces off the board.