Marcelo explains various details for nailing the Armbar from the Crucifix Position: Keep your body contracted to maintain position, especially if your opponent is strong and induces a roll. Expand your body to apply pressure against their elbow joint; stretching too early may be the cause for losing the submission. Crunch inward and hold yourself tight against your opponent's back with Seat-Belt Control until you find the right opportunity to attack their arm. When on top against your opponent's Turtle, keep your weight focused on their arm while still covering their back. Don't lean too far in any particular direction, unless you are directly opposing your opponent's attempt to change up the position from bottom.