It wasn't too hard to foresee this position, even as far back as the eleventh move. Three pawns for the piece, a powerful, passed e-pawn, the possible check on f7 at any time, the open a3-f8 diagonal for the dark-square bishop, the central files for the rooks, and Black's backward queenside development all point to an excellent game for White.
But Black does have an extra piece. This means White will have to be very accurate in his attack. Any little slip could give Black the advantage very easily.
Black continues to develop pieces. He does so with a gain of time as well, since this move threatens to win the Exchange.
White to move. What would you do?
Where should White put the rook? Does it belong on the open d-file or does it need to back up the passed pawn from e1? White makes the wrong choice because of being overly concerned about having his rooks on e1 and a1 with a possible Black bishop coming to c3. But that will never happen if the e4-pawn marches to e5!
Correct is 16. Re1! Rooks belong behind passed pawns! After that, 16…. Nfd7 17. Bd2 gives White a powerful center and a big advantage.
The move played is a case of the wrong rook going to the right square. After this mistake, Black takes over the initiative, sacrificing the Exchange to do so.
Everybody makes mistakes, even very strong players. When you notice that something has gone wrong, keep your head. Assess the position and make new plans. It will not help to berate yourself or become discouraged during a game.
16…. Nbd7 17. Ba3.
The a3-bishop and f8-rook are now on the same diagonal, with only a White knight in the way.
You cannot carry out any tactical plan without carefully preparing for it. The position in front of you may contain hints of what to look for, but you have to be able to interpret those hints.
White sets up a discovered attack by bringing this bishop in line with the Black rook shielded by a knight that can move with check. Discovered attacks don't happen by themselves: They have to be set up.
Black gives his king a better square to go to than g8, which is exposed to the White b3-bishop.