Oh, I would also like to add this: When you are standing in front of a boss before the pull and you are waiting for the healer or DPS to get ready and you are sitting in 5 stacks of wrath and watching them tick away, if you have just a few seconds left, popping unchained is a great way to use up those stacks and not let them go to waste, so when you rush at the boss you a have a really decent way to front end your damage and establish loads of threat right from the get go.