Picture the scene: your mum walks into GameStop. She walks to the Xbox 360 section, and picks out a game for your birthday. At random. What are the odds she picks a good one?
Market research firm EEDAR are on-hand to help you find out. Having tracked every Xbox 360 game's score in Metacritic, they've found that 13% of Xbox 360 games average a review score of 85 or higher. That's 48 games. Leaving 49% of games scoring between 66-84%, and 38% of games scoring 65 or lower.
So odds are good she'll get you a game that's... well, if not Crackdown, then at least halfway decent.