This is what I have been teaching and preaching for years. This is fully explained in a segment by pitching coach Rick Peterson when it comes to pitching mechanics, velocity (where it comes from), etc. He explains the epidemic of Tommy John surgery and where the stressors in the arm are coming from which is all caused by rushing and timing problems. It is shown in flat arm when front foot lands, landing on heel, bringing elbow above and beyond the shoulder, pre-pronation, etc. I wish there were more guys like him.  This is a must watch for coaches and players!