There's a lot of information on here, and I just kind of skimmed over a lot catching up. The one thing I notice with many blast results in general being odd or off where all are trying to pinpoint one thing... IF you have a bat that's borderline heavy or too long for them, you will see drops come in across many areas on your blast scores regardless of proper teaching technique. The moment the hitter can't control their bat path due to weight or too long, you'll see issues or they won't be able to clean up areas you are working on. It really is a HUGE difference that you are indeed verifying the correct size and weight of the bat for your kid. THAT would be my first question, especially at ages 8-14, because theres a monster varience to growth spurts.