Two factors would make this difficult:
1. The most powerful cards are not always known until a few months after the release, after people play with them inside the game and learn how they interact with other cards.
2. Especially in Magic, the game is played half the time with sealed packs in draft format.
Tournaments determine the value of the rares, and sealed packs are valuable for testing and practice.
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Last edited by Rian Fike; 01-07-2013 at 08:40 AM.