the rugby subsitute "issue" is probably being blowing out of proportion , but what do we mean if we say boks got a edge from it? how did they specificaly benefit? it is not just "fresh legs" because all teams has that option.

no , it was a tactical benefit.

in the nutshell , the 6-2 split was final piece of the puzzle of the bok defence..

boks had second pack of tight forwards on the bench because the way the forwards defend in the Bok system is cornerstone of everything else.

the Bok D line speed is technicaly led from the outside-in , but there is also a mini rush inside , where our forwards go up fast to hit the first pod , or the first carry - the "momentum" carries of the opponent. if this tackle is dominant, then the oponent is already in trouble

because now the offside line is IN FRONT of you and your defenders can play forward. it is much harder to be aggresive if you first jogging BACKWARD to stay onside and then you still want to get ready to try rush.

1) dominant hits puts all your defenders in sprinting blocks.

2) dominant hits also slows the ball down, and that give aggresive Bok D time to set - a crucial ingredient

we think of slowing the ball at the ruck , but that process START in the tackle. dominant hit take away your oponent quick ball AND then make it easier to slow at the ruck

Boks liked to send a extra defender to breakdowns to slow the ball , so when you taking this numbers risk it is very important that your line D is ready and set on OWN terms. and for that they need a extra second or so. dominant hits was a "non negotiatable" part of Bok system.

so you see if Boks took foot off gas for a few minutes then it all unravel. D lose some ability to be agressive , they will get caught by quicker ball, and the risks in their system will come to light. Boks can not really go into a state where they just "absorb" the attack.

the whole thing rely on what happens INSIDE , with forwards getting up FAST and then throwing everything they have into tackle to ensure it is a dominant hit.

@RugbyAnalytics say' the RWC tournament average for dominant tackles was 35% , but Boks sat at 69% dominant tackles...

that "rushing and wrestling" is incredibly hard work trust me ! so you will burn through forwards like Eskom burn through coal.
hence a second tight five on bench to keep the corner stone of the D functioning for 80 minutes.

but do you agree it is ultimatley a tactical edge?

so it is silly I believe to try and legislate against this "edge" that substitutes can give you . rather try and find your own tactical response... Attack and Defence is always locked in a struggle of inovation , so rather let coaches find the answers than doing it in a law book.