Bloodbowl - throw a rock, roll for injury or casualty?
Always roll for injury first.

Roll against casualty table if injury roll result is 10-12.

This is similar what you do when a player gets pushed or knocked off the pitch and gets beat up by the fans.

My rule interpretation:
The rule would most likely also say "No Armour roll is required and No Injury Roll is required" if the intent was to go directly to the casualty table.