I wondered about this incident, and found it on YouTube. It was the best evidence on Jean's pace in rugby boots one could get.
Firstly one has to say le Roux was probably at pace earlier than Jean, so if anything this understates the case.....call that an offset for Willie carrying the ball.
But the first time you see both players in context Le Roux had 68m to the tryline and 16m to the touchline. He scored on the touchline so that sets up your triangle.
Jean had 65m to the tryline and 35m to the touchline. The players run along the hypotenuse of the triangles. Solve for the hypotenuse of both triangles and we find Willie covered 69.8m and Jean covered 73.8 metres. But Jean was a metre short when he got to Willie, so call the gap 3 metres.
I don't know how fast Willie is, but there is no doubt he was flat out all the way. His few looks were no more than a sprinter does as he is being closed from behind. I thought Jean was closing him rapidly but then started to tie up a bit at the end. The evidence is indisputable Jean was travelling faster than Willie for much of that run.
There may be a reason for dropping Jean from the Boks, but pace is not that reason.


