I never read anything about gameshape either.
But both of you are correct about the phisicality. He says that players with high phisicality gets injured more often. You say its random. I think it go as this: Each time a player is fouled there is a random small chance that he gets hurt. So in that instance you are right. But as players with more phisicality trait gets more fouled, he has more opportunity to get injured. So he is right, physical players tend to get more injured.