"Great chess players usually excel at both position and tactics, I'm not sure one can get very far without getting a feel for the interaction between the two. This game's a great example how even early in his career Petrosian was very skillful.

His getting the N to e3 and 17.f3 shows the intent on controlling the White squares which positionally/strategically keeps Black's pawns on dark squares which in the end game is a weakness as long as White keeps his QB. White square control also restricts the undeveloped Black QB which gives White time to take advantage of the semi open c-file where Black is bound by d5, a positional plus.

The tactical part is how to expolit the advantages. A lot of that has to do with timing. As Suetin wrote in his notes, around move 17-20 Petrosian plays energetically to get to them before they can be defended.

The way it played out, and not by accident, by move 24...Qd4, Petrosian through his tactics from 17.. to 24.. probably produced a strategically won game. White has invaded with the Rook, Blacks got the iso stuck on a dark square with very weak pawns on the b & h file. From this position Petrosian has to figure tactically how to best take advantage which he does fairly easily.