according to the law, re. tackling a player in the air (this has nothing to do with CJ stander's who was trying to charge down a kick):
Law 10.4 (i)
Tackling the jumper in the air
A player must not tackle nor tap, push or pull the foot or feet of an
opponent jumping for the ball in a line-out or in open play.
Sanction: Penalty kick
At a meeting in April 2015, the Laws Representation Group (LRG)
of World Rugby (previously the International Rugby Board) considered the
areas of the Game where, it had been agreed that Law amendments were
not required but that current Law was to be enforced by match officials
including:
Challenging players in the air - Law 10.4 (i)
The options given were:
Play on – Fair challenge with both players in a realistic
position to catch the ball. Even if the player(s) land(s) dangerously,
play on
Penalty only – Fair challenge with wrong timing - No pulling down
Yellow card – Not a fair challenge, there is no contest and the player is pulled down landing on his back or side
Red card – Not a fair challenge, there is no contest and the player lands on his head, neck or shoulder
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in my view, Le Roux arrives late,.... that's why he jumped very horizontal (instead of jumping high to try to catch the ball) and that's why he "tap, push or pull the foot or feet of an
opponent jumping for the ball".
So there's not a fair challenge and "the player lands on his head, neck or shoulder" very dangerously,...... it should have been a red card
But what you are proposing it's almost impossible to happen (if not impossible at all),..... the Irish falls so badly because he's hit on his legs what makes him give a 180º turn in the air,.... to make possible for Le Roux to reach the ball he should have jumped with the correct timing and higher in which case he would have hit the Irish trunk and this last wouldn't have turn 180º in the air.
If "Le Roux had gotten his hand onto the ball and played it backwards",
it would have meant that he wasn't late and that both players contested
the ball colliding with their trunks (instead of Le Roux trunk hitting
the Irish legs), so the Irish wouldn't have landed on his neck . In this case is very probably that not even a penalty
would have been called.