I think you are trying to say mastery is better if you are off the target more because it is ticking. Expertise is also really good if you are getting off target a lot though. If you are off even a relatively short time you will energy cap and at that point having your stuff dodged is wasting energy and also delaying combo points if you need to refresh something. If you have been off a while or are opening, having stuff dodged will significantly increase your ramp up, such as having your mut dodged preventing applying rupture or SnD. Again its about variance.