Kt-B3 would have been slightly better, because the Black QKt might play to his K4.
7. … PxP 8. KPxP Kt-Q2 9. P-B4
This move weakens the King’s position, and would be justified only if there was a possibility of opening the file for the Rook by P-B5. But Black has too strong a hold on his KB4. The text move aims at preventing the exchange of White’s KB through Black’s Kt-K4. It would have been better to withdraw the B to B2.
9. … Kt-KB3 10. Kt-Kt3 P-KR4!
Now White cannot enforce P-B5, as Black can attack the Knight by P-R5. White cannot prevent this with P-KR4, as the Black Knight would take up a commanding position at Kt5. Black’s game is superior. He can concentrate all his minor pieces on the King’s wing, while White’s QB is ineffective on account of the ill- considered advance of the KBP.
Diag. 163
11. Castles P-R5 12. KKt-K4 KtxKt 13. BxKt
White has to capture with the B, in order to exchange the Black Knight if it should play to B4. After 13. KtxKt, B-Q5ch; 14. K- R1, Kt-B4; White’s Knight would not be able to move from K4 on account of the threat: Kt-Kt6ch. Sooner or later, Black would get a deciding advantage by enforcing the exchange of White’s Knight, e.g. 15. Q-K1, Q-K2; 16. R-QKt1, B-Q2; 17. P-QKt3, Castles QR; 18. B-Kt2, QxKt; 19. BxQ, Kt-Kt6ch; 20. QxKt, PxQ; 21. P-KR3, BxP; 22. PxB, RxPch; 23. K-Kt2, R-R7ch; 24. KxP, RxB; or 21. BxB, RxPch, followed by PxB and QR-R1.
13. … B-Q5ch 14. K-R1 Kt-B4 15. BxKt BxB