We have terrible technique and not enough commitment when tackling. There needs to be more leg drive, shoulder (less arm-grabbing), commitment to go to the ground to make the tackle effective. Tacklers often work against each other rather than driving the ball carrier in the same direction. It all adds up to missed tackles, off-loads and lack of dominance in the ruck.
Watch the other top teams, they work together much better and actually look like they are well trained in how to tackle as an individual and how to hunt like a team in this area.