Do you want to simulate combat, or do you want to use game rules to resolve the combat?
D&D was designed not to be a simulation. The attack roll represents whatever it takes for you to cause damage. Damage represents whatever you've got that keeps you alive and kicking. In those terms, you make an attack roll for wrestling just like any other kind of attack. The damage isn't going to kill you, but it will prevent you from fighting any more if you take enough of it. So do what the SR examples does, and you'll be using the rules at their fundamental level.
D&D was designed not to be a simulation. The attack roll represents whatever it takes for you to cause damage. Damage represents whatever you've got that keeps you alive and kicking. In those terms, you make an attack roll for wrestling just like any other kind of attack. The damage isn't going to kill you, but it will prevent you from fighting any more if you take enough of it. So do what the SR examples does, and you'll be using the rules at their fundamental level.
