John Sickels' Minor League Ball has a piece on how Wandy (or, "Eny Cabreja") broke out last season, and has put together a decent Major-League career, despite never being graded higher than a C+ as a prospect.
It's a nice recap, and closes with:
Rodriguez is now 31 years old. His development curve has been unusual, and he's become a much better pitcher than his minor league track record would indicate. I don't really have an explanation for it, other than weird things happen with pitchers sometimes. This is a good example of how a Grade C pitching prospect can still develop into something very interesting.