World of Warcraft Class Talent Q&A

Blizzard's official World of Warcraft community website has been updated with a new Q&A that offers some feedback from lead game designer Tom "Kalgan" Chilton about how the team evaluates class talents. An excerpt:
Q: At which point (or points) during a class talent review do you step back and evaluate how the talent changes for this class will affect other classes that fill out similar roles, like priests and Restoration druids?

A: Evaluating how changes will affect other classes that fill similar roles is a constant part of the entire design process. We need to keep in mind that character classes don't exist in a sterile Petri dish, but instead interact with many other different classes either in groups or in PvP situations. If we go too long without taking a step back to evaluate the impact on the game as a whole, we run the risk of spending too much time on an idea that will have to be thrown out later down the line. That's why our balancing process goes through several phases. When we're first designing how each talent or spell will work, we decide on our philosophical approach to balancing it.

Some of the considerations are the talent's power relative to other talents, its location in the tree, whether it compounds the effects of other talents or spells (including those of other classes), and how important the effects of the talent are to that character class as a whole. Basically, how does having or not having this talent affect the class' performance in its role? Also, if it's an active talent, we first want to determine the actual gameplay situation in which we think the ability will be useful. Once we have a good idea of when and how players will use the ability, we can balance the numbers to support the design. Most of these fundamental balancing decisions begin at a very early stage of the process, but they are also constant factors during the entire length of the design cycle.