I understand what you mean thomas however, it should be noted that usually a Bf3 is the same as a Bg2 - very powerful on the long diagonal but in this situation it is hitting the d5 square - blacks strong point and there is no future for the bishop. Therefore this trade is good for black. It also weakens the c4 square which will allow Nd6 (protecting the bishop) Rc4 (gaining time) Qc7 and Rc8 with a massive battery.

I like Nd6 - getting the knight off the back rank and protecting while keeping Rc4 in store. This also invites Be3 as ion states in the next post.

Black might have found 20.Be3 a bit of a nuisance. Black has to find a defence against Bb6 and Bc5. True, 20...Qc8 21.Rac1 Nf6 seems to hold everything (22.Rxc7 Qxc7 23.Rc1 Qd7 24.Bb6 Rc8), but one always has to be on the lookout for possible tactical shots like this. *** It turns out there's a fair bit of low cunning behind the text move, too, that black doesn't spot betimes...

(!) Black's 20th was an oversight...

(?) White could have won the exchange here! 22.Qxf8ch Qxf8 23.Bxf8 Kxf8 ... After 22.Qa5 Black can avert loss of material by 22...Re8.

A mistake true but as thomas shows there is plenty more fight for black in the position. A few reasons why: A massive centre is ready after e5, the lack of pieces on the kingside inviting an attack. Combined with the c file battery (whites rooks dont coordinate) black should have drawing chances. (Or in this case winning chances  )

Sacrifice or oversight? For the exchange Black has (had) an extra pawn, a protected passed pawn in the centre, and a mobile central pawn majority. White has the Q-side pawn majority that might become a major player. Black's problem child, it seems to me, is the light square bishop - a "bad" bishop so-called. Before this rook move, White seemed to have a slight edge...

If it weren't for the hanging pawn this would be good preventing the e5! pawn break by black. I kind of dont fully agree with ion about the bad bishop - it is bad but has potential to be good. (when the e5-d5 pawns are there).

Preventing the battery from ever forming on the c-file and therefore decreasing the co-ordination of blacks pieces. However, the queen finds a new home on b8 to aid the e5 advance.

Just to clarify: 27.Re2!! would have been pretty neat, as it forces a rook exchange. There's nowhere to hide on the b-file. 27...Bc6? won't do owing to 28.Rxb2 Qxb2 29.Qc5ch, picking up the bishop. After 27...Rxe2 28.Bxe2 White threatens to win the a-pawn at once with 29.Bxa6; but even nastier is the idea of 29.Qb6!, when the bishop will be pinned like a bug. The only move to stop this seems to be 28...Nd7 but 29.Rc7 drives it off. It looks as though White's pawn investment could indeed have reaped dividends...

Bf3 was a move that was probably afraid of d4, and then e4, when the central pawn storm pays massive dividends...

Possibly just to block the 2nd rank. White is being thrown increasingly on the defensive it seems to me. Maybe he ought to be looking to simplify (exchange down) by 30.Re2, and if Black won't oblige, to double rooks on the c-file.