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Material is exactly equal: R+B+4P (and both bishops are DSBs), and yet white is clearly better because of mobility issues.

- The black pawns are all on dark squares and the white pawns are all on light squares. This means that black's DSB is hemmed in by its own pawns, and while it can defend his pawns, it cannot attack the white pawns. The white DSB has much more mobility and it can attack the black pawns.

- White's rook is strongly placed on d7, keeping the black K trapped on the back rank. It can make threats against black's two backward pawns (Pd6 and Pf6). The black rook is more challenged. It can make threats againts white's lone backward pawn (Pf3), but the white king has somewhat better prospects for venturing out if its hole. Also, the white king doesn't need the DSB for blocking checks since he is shielded by Pf3.

Clearly then, black is playing for a draw, while white is entertaining hopes for a win.

It appears that black should be able to hold the draw. In his favor are: (1) a rook exchange at this point is drawish, and (2) the white king is saddled with the defense of the Pf3.

However, black's main vulnerability is his Pd6. This backward pawn can only be guarded only by the black DSB. This fact should guide black's defensive play: <Black must make sure that white cannot make a successful double-attack against this weak d6 pawn>.

A few moves later, we arrived at this position (after 51.Rb7):

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Here black played <51...Re2?>.

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This move accomplishes nothing, and worse, it neglects black's main objective which is to not allow double-attack against the weak Pd6.

White didn't waste the opportunity: <52.Rf7!> forking the DSB and Pf6, forcing <52...Bg7 53.Rd7> attacking the weak pawn. Note that attacking Pd7 immediately with 52.Rd7 isn't as good because it gives black time to play 52...Ra2, which prevents Ba3.

With his rook uselessly on e2, black must defend with the DSB <53...Bf8 54.Ba3>

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And there it is: the successful attack on the weak Pd6 that black needed to prevent. <54...Kg8 55.Bxd6 Bxd6 56.Rxd6 Kf7>

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White has a deadly protected passed pawn. Furthermore, a rook exchange now works strongly in white's favor. I believe the game is winning for white at this point. It's still not a trivial win, but white used good technique, bringing his rook to the 2nd and 3rd rank to shield his K and guard Pf3, and he used rook-exchange threats to advance his king for offensive purposes, ultimately earning the win.