Albertan: The move 6.Bd2 is a rarely played idea in top-level chess. Usually White plays 6.Qc2.
The move 9...a6 has only been played in one other game besides this one:
Atalik-Erdogdu, 2003EU-ch 4th.
By playing the move 9.Qc2 the game tranposed back into the main line.
It is more popular for White to play the move Bd3 on move 11.
Another idea on move 13 was to play 13.b4 with this variation possible:
13. b4 Ncd7 14. Ne4 Be7 15. Rfd1 Bb7 16. Nxf6+ Bxf6 17. Rac1 Rc8 18. Qb3 Qe7=
The move 22.b4? was a mistake. Instead he could have played 22.Be2 with this variation possible:
22. Be2 Rfd8 23. b4 Bd4 24. Rf1 Qa8 25. Bb2 Nxe4 26. Nb3 Bxb2 27. Qxb2 Ng6 28. Rxd8+ Rxd8 29. Rc1 Nf4 30. Bf1 Bd5
Starting on move 25 Kramnik could have gained more of an advantage if he had played the move 25...Qg3! with this variation possible:
25... Qg3! 26. Re2 f5 27. Qb3 fxe4 28. Qxe6+ Kh8 29. Qd6 Qxd6 30. Rxd6 exf3 31. Rxf2 fxg2+ 32. Bxg2 Nxf2+
On move 29 Kramnik could have played the sacrifice 29...Rxf3!! with this variation possible:
29... Rxf3!! 30. gxf3 Qxf3+ 31. Bg2 Qf5 32. Bxb6 Qh5+ 33. Kg1 Qh2+ 34. Kf1
Rf8+ 35. Ke1 Qxg2 36. Qd3 Bxe4 37. Qe2 Qh1+ 38. Kd2 Qb1 39. Qxe4 Qxe4