In the variation given in the note, Black has just played 17...Ra8-c8, 'with a powerful bind'. The Knight on d3 prevents the White Rooks from playing to the c-file, while the Knight on d4 is pinned by the Bishop on g7. If White exchanges the light squared Bishop for the Black Knight, White will have light squared weaknesses on the Kingside. If White plays f2-f3 to undermine the Knight's protection, the Pawn on e3 will become weak. White's predicament is reminiscent of a Kasparov brilliancy from his second World Championship match with Karpov, where a Black Knight on d3 also created serious problems in the White position.
Byrne avoided this variation, but was hit with a powerful sacrifice of the Knight on f2 that opened White's King position to Black's diagonal pieces. Instead of losing positionally to the bind, he lost tactically to a Kingside attack.
