White worked hard to reduce the value of the dark squared bishop - but his c3 pawn weakness is on an open file. Being able to point my rooks at c3 and have Be7 pointing at b4 makes some tactics to gain a pawn on that strong chain.
16. Nd2b3 Qd8c7 17. Ra1c1 Bc8b7
a6 is the queenside pawn weakness, if I break the queensides pawns, and get a rook behind whites pawn structure, I will need to be able to defend a6 or else I'll lose a pawn trying to save the dark squared bishop after Bxb4, Bxa5 Ra1 and a6 falls. This square is best - and right now I need to do some rearranging to get my rooks on the c file.
18. O-O Ra8c8 19. Rf1e1 Bb7a8
To allow me to play Qa7. Bb7 is still the best square, but this is allowable as long as the queen stays on a7