karpov v. taimanov, moscow, 1972

in anatoly karpov v. mark taimanov, moscow, 1972, both players seem to accept a lot of even exchanges, at least until karpov's end strategy.  How can I understand this?  Is karpov (and/or taimanov) simply exchanging pieces in order to get to their end game?

many thx for taking the time for the great answer.

The game is very likely annotated by Karpov himself, in one of his best games books.

Yes they're trying to get the right setup for a specific attack. And exchanging pieces is a means to develop to that end. It's opposed to blindly exchanging pieces to simplify the game; there's a precise reason for each exchange related to the player's long-term thought process.

You asked to be embarrassed. 

Move 17 "Not exactly sure why the f Rook over the a Rook?"

Because after 17.Rac1 the move 17.. Bb5 wins on the spot! SKEWER! 

In the Immortal words of Homer Simpson "Doh" Thanks missed the skewer lol

I do not understand 15 Nbd2, allowing the freeing 15...d5.
Why not the natural 15 Nc3, which impedes 15...d5

I do not understand 23...Na5, putting the knight on the rim.
Why not trade the central knight 23...Nxd4.

Can't find the game annotated by Karpov himself. In an old best games book by Markland gives 15Nbd2 leaving no choice because intending Nc4-d6. It implies black didn't particularly want to play d5.  23...Nxd4 inferior because white comes closer to goal of simple endgame.

Predictably enough software doesn't agree with these assessments.