I don't know if I can add to this discussion but I will try. I fully understand the need to know where your son is at in his development. For those of you that have one son maybe two? I have four.... and all for are different. They all have their strengths and weaknesses All matured and developed at different times. My sons are between 6'2 and 6'5 and every time they grew a little we had to re-learn the mechanics for the new frame.
I have hard throwers, soft throwers, fastball/slider at 3/4 and fastball/12-6 over the top. In fact the biggest one is 2016 at 6'4 200 and throws the slowest. I guess my point is you can drive yourself crazy with velo numbers but it really is going to be what it is going to be. You can add some as you get older and get man muscle but don't expect any huge gains. Instead learn how to pitch....learn how to to get the batters out.
It seems with all this talk about 9,10,11, 12 velo.... what type of mound are they throwing off of.... 50 feet?
One more thing, in years past I was sooooo worried about 2013 and 2014 that I kinda let 2016 and 2018 just do their thing .... I went with the older two.. dragging them around the southeast watching every scout, radar gun etc... trying to increase velo... taking pitching lessons.... from USA to Area Code to PG
While my wife took the younger two to their local games and maybe an out of town tourney. I just thought logically that when the younger two were older I would work with them.
I would call my wife and rant and go on and on.... 2013 did this 2014 didn't do that.... and then when she told me about the younger boys it was like , they did fine...we don't play til later tomorrow, so we are going to sleep in and go swimming... SWIMMING , are you crazy on game day !
My point is stop stressing about all this velo stuff at the younger ages.. enjoy the ride... what will be will be, it goes by fast.... and remember the thing tht is more important than throwing 90+ GRADES !
Oh and im 6'4 250 and my velo is 55 , tore three cuffs 6 years ago.... talk about pain