Principles of throwing: 90 degrees
One of the essential principles of an efficient throwing mechanic is to open the elbow straight back after ball separation from the front hand to a position of 90 degrees in the elbow and 90 degrees in the arm pit. An elbow lower than that will have to come “around” the axis of the torso creating an arm mechanic that increases chances of missing targets laterally. Since this mechanic is essential, the key is now to get to that point as quickly as possible, with no wasted motion that adds unneeded time to the delivery. A common mistake is taking the ball down and around, and looping to get ultimately in that same position to bring the ball forward, so it simply makes sense to eliminate all unnecessary motion.