Solid defence demands teams have fluid lines

TOKYO, 5 Oct - The fundamentals of attacking structures have been examined; now we look at defensive structures.
The job of a defence is simple: do not concede points and win the ball back at the earliest opportunity.
Over time defence coaches have decided that the best way to defend is with players in a flat line. We call that the defensive line. If you put 15 defenders in that line, it would be very hard to break through, but it would be easy to kick over the top and into the space. Teams, therefore, drop players out of their defensive lines to cover the kick.
Finding the balance between players in the defensive line and players covering kicks is key.
In the clip above, Ireland start out with three defenders covering the kick. Three defenders deep leaves 12 defenders in the line, so we call this a 12-3 defence.
Watch how that defence mutates as Japan move the ball to the left and then the right. The Irish wingers step into the line when the ball comes towards them and the Irish defence is now a 13-2. When the ball is in the middle it becomes a 12-3 again. Then when the attack is on the far right, it is a 13-2 again. When Japan break through the middle of the line, Ireland move fully to the 13-2.
The Irish defence reacts to the threat posed by Japan. When the Japanese are far away from the Irish line, the defence can afford to drop more players back for the kick. As the Japanese get closer to the Irish line, the threat of the kick diminishes. At that point the defence puts more people into the line and leaves two players to cover the entire back field.
Watch how Will Hooley of USA defends close to their line. The Americans are in a 14-1 defensive formation. This close to the line, you do not want to drop men out of the defensive line in anticipation of a kick which almost certainly will not be forthcoming. Hooley's job is to bounce back and forth, and cover the defence. If there is an overlap, he will step into the line to help. If there is a defensive hole, he will step in and sort it out.
The full-back's job, close to his own line, is to anticipate where the attacking threat is. He then has to decide when to get involved and when to stay back. If he does stay back, he has to be prepared to make one-on-one tackles on players carrying a lot of speed. It is not a position for anyone who feels nervous under pressure.
Next time you get the chance to see your team live, look to see how they defend. Do they drop more men into the back field when the opposition are close to their own line? How many players do they drop back? Which players are they dropping back? Is it just the full-back and wingers or is the number eight or scrum-half involved?
RNS sl/sdg/mr