When you ask me, reviewers tend to give under-anticipated games on the Wii higher scores.
It's as if they enjoy being the minority. If anything, there should be a component of the Metacritic scores that are proportional to the game's sales. (So high selling games get boosted and low selling ones get penalized)
My collection of guides on GameFAQs: Read them here
My latest guide on GameFAQs, for Little King's Story! Read it here