ThinkTank- Well if you're comparing the video to the one from last year there was a heap of stuff that changed. But more recently, it has been really using the back hip more efficiently and not wasting energy, trying to move quicker towards the plate. Before I would lift my leg up and then turn it, now I'm lifting it and going straight to the position where I start moving forward. Keeping my front leg internally rotated has always been pretty good for me, I never actually focused on it but I think it is a by-product from using my hips more efficiently.
Rugby- Thank you, at age 14 I definitely not one of the hardest throwers, I was like 67-70 I think. My advice to anybody younger, would be throw it hard, and get a feel for a change up. Really learn efficient mechanics, don't listen to close to 90% of people who want to tell you about proper mechanics and training, do your own research. I had help in my journey but for the most part I taught myself how to throw 90+.