Why isn't there a big advantage in this position for black? I was browsing some interesting games, and found this one "Jerzy Lewi vs Jan Adamski" (1969):

[fen "r1b2r1k/1pq3bp/8/3Qp2n/1P1n1pp1/2NP2P1/3BPPBP/1R2NRK1 b - - 0 0"]

1... Qxc3 2. Bxc3 Nxe2+ 3. Kh1 Nxc3 4. Qb3 Nxb1 5. Qxb1 f3 *


(note: the game continued, but I want to focus in this position)

From this position, the white bishop is inevitably going to be taken, so we can say with certainty that the captured material difference is R+B+B vs Q+(possibly a pawn).

To my perspective, black's advantage is notably greater, however chess engines says that white is behind only by about -0.70.

How is that this apparently crushing advantage turns out to be just a small advantage? What am I missing here?
Here's a variation from Stockfish.  What we see is that after the smoke clears, Black's advantage actually is pretty small.  Here's why:


If we just 'added up points', which is not a bad way to get an immediate feel for a position, we'd see White is down a single pawn, 13 vs 14.
We also notice White has two pawn islands of two pawns each.  Black has two pawn islands but one of his pawns is isolated.  This is a slight advantage for White. Further, if Black connects his two-pawn island, his King will be completely exposed.  In reality, all of Black's pawns are isolated and will have to be defended by pieces.
Black's King is exposed; with White's Queen on the board any mistake could lead to a perpetual check.
Black's Bishops obviously can't protect each other.  Given the exposed Black King, any of Black's pieces could be picked off by a Queen fork.  Black will have to be very careful to ensure he doesn't lose material to the rampaging Queen.


Items 3 and 4 will make it hard for Black to go on the offensive.



[fen "r1b2r1k/1pq3bp/8/3Qp2n/1P1n1pp1/2NP2P1/3BPPBP/1R2NRK1 b - - 0 0"]

1... Qxc3 2. Bxc3 Nxe2+ 3. Kh1 Nxc3 4. Qb3 Nxb1 5. Qxb1 f3 6.Qc1 fxg2+ 7.Nxg2 Bf5 8.Rd1 Be6 9.Kg1 Nf6 10.Qc7 Nd5 11.Qxb7 Rab8 12.Qa6 Rb6 13.Qa5 Rxb4 14.Ne3 Nxe3 15.fxe3 Rfb8 16.Qc7 Rb1 17.Rxb1 Rxb1+ 18.Kf2 *