For me, I feel that the tanking meta has slowly shifted over recent years, but going back to older content has been a sharp return to the old meta and the newer tanks can't cope with it. There are pretty much two types of tank in this game. 'Turtle' tanks, who curl up into a ball and take everything that's thrown at them, and 'Kite' tanks who constantly move around the room, dragging all the enemies behind them. In the most recent episodes, the meta shifted towards 'Kite' tanking, (which I personally hated...) but now we're back playing older content, 'Kite' tanking doesn't work as well because you're forced to hold your ground and 'Turtle' a lot more. 'Kite' tanks are set up differently, so generally they can't hold that much aggro at once, and tend to die fairly quickly when they're suddenly required to hold their ground. Personally I've always hated 'Kite' tanking. It's always felt like a somewhat selfish and impatient playstyle, and it's really annoying trying to chase after a group of adds when you're a dps. I've always been a 'Turtle' tank, and I love it, purely because of the fact that I can walk into a room and just take control of the situation, take the heat off of my team and keep all the adds in one place for them to just light up. I think that's why there are less tanks around at the moment. Too many 'Kite' tanks who can't stand their ground.