Now that I think about it, the cause-and-effect here is probably being viewed all wrong.

What likely happens is that a game comes out to overwhelming expectations, and the greater those player expectations are met, the more word-of-mouth gets around about the game. Thus, games that deserve to do well make more money, and pirates are less motivated to work on a crack right away.

If player expectations are not being met, the less success the game receives, and the more motivated pirates are to crack it (driven by their disgust at bad software).

The above scenarios probably do a good job of accounting for 20% of the revenue for a game.