If we want to be serious for a second... one of the hallmarks of the Roosters under Robinson has been incredible linespeed in defence. Their halves push up really fast to cut down potential shifts to edges, and they have a very upright tackle technique to wrap the ball up and spin attackers onto their backs. That opens itself to more headclashes and potential HIAs, and I reckon would account for a few of them
However...
Cordner and Tedesco both had a heap of HIAs and the majority of them were from getting their heads in the wrong position down low (Cordner) or from a very unusual running technique (Tedesco).
So who the hell knows
