TOKYO, 23 Sep - Rugby defences are always trying to reduce the opposition's space and time - that is the key to stopping an attack, winning the turnover and hopefully scoring a try.
One way to do that is to blitz the opposition's attack. When you blitz, or have high line-speed as you may also hear it described, you are getting off your defensive line quickly to reduce the amount of time the attack has.
Faced with a blitz defence, the first receiver has very little time to decide what he wants to do with the ball and then execute the skill of passing or kicking.
However, a blitz defence also increases the space the attack has. When 11 or 12 players come rushing up it is hard for them to stay in a line and when they do not stay in a line they create gaps between themselves. That is the pay-off of reducing the opposition’s time.
In this first example, from Sunday's Ireland v Scotland game, Irish captain Rory Best explodes out of the line to reduce Scotland fly-half Finn Russell’s response time. Ireland already know what Russell will do because they have reduced his options down to just two: he can hold on to the ball and get hit behind the gain line, or he can tip the ball on and Ireland will tackle Scottish captain Stuart McInally behind the gain line.
In the second example, below, Ireland's Gary Ringrose has one goal: he wants to catch Russell behind the gain line. Again, Scotland are left with just two options: Russell can carry and lose metres or he can pop the ball to winger Tommy Seymour. He decides on the latter but as he has less than a second to complete that skill, it goes awry and Scotland end up defending a five-metre scrum.
It was not just Russell who was in Ireland’s crosshairs. In the next video Scotland have a two-on-one overlap. Jacob Stockdale realises this and decides to close down Stuart Hogg’s space. If he was not being rushed, Hogg would be able to complete this pass with ease. When he is given just a bit longer than the time it takes to blink, the pass is not as successful.
Constantly playing with quick line speed exhausts defences. They are sprinting out, jogging back onside, and sprinting out again. No team has yet found a way to be fit enough to do that for 80 minutes and because of this there are times when teams opt not to blitz, still cutting down the opposition's time but not at such rapid pace. When Russell is given the time to do what he wants with the ball and the time to execute the pass, he is obviously much better.
In this final example, Scotland gain metres but when they get nearer Ireland’s line, the blitz defence returns with a vengeance.
Ireland’s line speed stopped Scotland’s attack from being as effective as it could have been. It does have its weaknesses though. As teams tire the players come off the line at different speeds and gaps emerge between them. If you blitz and fail to get there in time, a good fly-half will be able to pick through the embers of your defence. Can Ireland keep this up all tournament?