There's a recap on Shacknews of "Making a Standard (and Trying to Stick to it!): Blizzard Design Philosophies," which was Rob Pardo's Game Developers Conference 2010 presentation. In his talk, Pardo looks at things they've done right and wrong over the years in game design. For example, he discusses the failure of the Diablo II economy, citing the economy in World of Warcraft as a success in comparison. Another case in point is made about hero units, describing the disappointment in how they are implemented in StarCraft, and how this was improved upon in Warcraft III.