If you want my take on Korchoi’s style, for those who have never really studied him before, it would be “Technical player/Defender” (he’s also known as a materialist). This is one reason that I think his style simply doesn’t match up well against Karpov’s (who is more vulnerable to a pure attacker). He had a strong record against Tal, for example, because he could simply defuse Tal’s speculative attacks.
Incidentally, I would call Timman’s style positional (Timman was essentially no threat to Karpov, IMHO, as I went over their match as well).
Okay, here is the game:
Korchoi – Suetin, Vilnius 1953
At first glance, you may see this game and not “grok” Korchoi as a non-attacking style, but pay closer attention. 20..Qg6? gets punished by an aggressive defensive reply.
23.Nxf5? is actually a poor attacking move, as Korchnoi states in his book ‘Viktor Korchnois Best Games’ that 23.Qxf5 would win material.
Starting with 25…Nbd5? (Korchoi recommends Rd7) Black commits a pile of defensive inaccuracies that Korchnoi notes. Now watch how Korchnoi just plays solid, so solid that his defense turns into an offense. Which of us would have played 31.Kf2! (?) One could make a case that Korchnoi essentially “out-defended” his opponent.