TBC was delayed but it was announced many months in advance and also it never had a release date. This time it seems the delay caught them by surprise and it seems to be mostly down to these unnecessary systems they can't balance or make fun. One example is that one of the biggest complaints about mythic+ loot is that if you had a bis item in there you have to farm that same item every single time the item level rewards increase, basically every major patch. Now they have extended that to affect every one by adding these conduit gems that you will have to farm every tier. The same ones, over and over. It will be 4-6 hours next week. Just wait.