In addition to the herding techniques mentioned above, I also break each side into four sections where I herd around the agro cap every time. Looking from the bowl you have: close middle, far middle, upper left, upper right. With the middles they each have a left and right side that can take some consolidation. So first I hit close middle and taunt/punchvoke both sides and then break los to herd towards the bowl like sbloyd mentioned. I then go back to get the far middle in a similar fashion but breaking los behind some door edges before following the same path as before. I then go back for an upper edge hitting the front group, then the back and then breaking los to hit again and then herd the same path.
What I would like in the future is organizing assigned sides for tanks so we aren't breaking agro on each other like sometimes happens. Like tanks on teams 1&2 take south, 3&4 east, 5&6 west. I've had a few runs where we instinctively got that figured out and we were all pulling some mega herds combined.
Attached picture from internet for reference: