Please, no one take offense, BUT FOR HS FRESHMAN AND YOUNGER, STOP THE VELO OBSESSION!
I can't count the number of young pitchers I have seen who are throwing beyond what their body is prepared to take - with the resulting career ending or career retarding injuries (needing TJ or labrum and taking a year off as a Jr. Is a disaster).
Building velo is a process - a long process with incremental or no improvement for periods following by noticeable increases (notable being 2 - 3 mph over a six month period). Many times it's because the growth spurt knocks the coordination off and NOTHING - ABSOLUTELY NOTHING - a PC can do can override that; moreover, trying to can lead to disaster. During puberty, the body development mostly drives the improvement; but during that time, dialing in decent mechanics, getting the kid to feel his body (so he's not just mechanically going through the motions) is critical; during this period, doing the correct PT will build up the body so it's prepared for the day when all parts are reasonably mature and ready to rock and roll.
Pulling out a radar gun on these kids is lunacy - because the kid pitches to the gun, exerting more effort which doesn't get any real velo and can lead to injury.
Put another way, no college coach cares, no scout cares, about what a 15 year old throws. This is a marathon and all too many treat it as a sprint - and have their kid sprinting a marathon is a recipe for disaster.
As the parent of a kid whose life dream was advancing to baseball's next level, it was a process with no fairy dust leading to success; it was hard, hard work for a long, long time with small improvements with no shortcuts.
PS. I am speaking as one who is able to pontificate from the other side (post-baseball). I am simply trying to offer the lessons we learned - I was just as obsessed as most during those HS and even earlier years (I was the crazy one with a radar gun on 12 yr olds.) We didn't understand s**t going through the process; now, I understand it. Fortunately, I got S to a PC before he got hurt from my well-intentioned involvement.