This article from The Premier League Owl, written about a year ago, is a good look at the de-valuation of Micah Richards. The conclusion is: it's a combination of him not keeping pace with Manchester City and a perception that he's injury-prone. But one isn't true and the other doesn't mean he won't fit in at Villa. The whole thing is worth a read as are the comments. Thanks to commenter birchgrovevilla for finding this!