I personally think that changing how each tank works is necessary. Right now it feels a lot like we can just take any two tanks we want and just have them do the exact thing. It creates a sense of monotony and the jobs feel very similar despite their differences. In my opinion, making it so that they at least have their core component be different should be the first step. After that we can talk on balance. Otherwise it's pretty much just pasting numbers and abilities from other classes. This is also a current problem with healers and Astrologian's identity crisis.