Yup its all about slim margins, Kolisi goes 3-6 inches higher and its a red card.
Yes its a bit of a lottery, change of direction, sudden drop, direct, indirect, bent, not bent, wrap, no wrap. If you go high you buy a ticket into the what card will I get lottery and yes its all about the slim margins at that stage.
But here's the kicker, you are under no obligation to enter the lottery, in fact you are encouraged not to buy a ticket, it wont end well you are told.
If you want to make a big dominant tackle by remaining high you are automatically entered into the draw, you don't have to but you cant complain if you do.
If you bend at the hip and go low, there will be no entry into the lottery.
Its simple really.