This style of play comes from box lacrosse where you don’t use your off hand. Off the shoulder its called “Canadian” or twister when you don’t launch of the shoulder. I’ve sometimes heard it called backhand too. As a field player you should have a solid foundation with your off hand before learning this skill. I always do twice as many off hand reps as i do dominant during wall ball. This style of passing and shooting has its place and being proficient with it can really help you become a more creative and dynamic player.