Here is what Michael J. Axe, MD, has published about youth pitchers and velocity expectations for 8 - 14 yo pitchers:
Age 8: Ave vel = 40 mph. 34% of 8 yos (1 std dev) will throw 43 mph. 13.6 % of 8 yos (2 std dev) will throw at 47 mph. 2.1 % (3 std dev) will throw at 50 mph. 0.1% (4 std dev) of 8 yos will throw at 54 mph. The 1-in-a-million category (0.00006 % or 5 std dev) for 8 yo pitchers is 57 mph.
Age 9: Ave vel = 43 mph. 34% will throw 47 mph. 13.6% will throw 51 mph. 2.1% will throw 55 mph. 0.1 % will throw 59 mph. 1-in-a-million will throw 63 mph.
Age 10: Ave vel = 46 mph. 34% will throw 50 mph. 13.6% will throw 54 mph. 2.1% will throw 58 mph. 0.1% will throw 62 mph. 1-in-a-million will throw 66 mph.
Age 11: Ave = 48 mph. 34% will throw 48. 13.6% will throw 52. 2.1% will throw 60. 0.1% will throw 64. 1-in-a-million will throw 68.
Age 12: Ave = 50 mph. 34% will throw 55. 13.6% will throw 60. 2.1% will throw 65. 0.1% will throw 70. 1-in-a-million will throw 75.
Age 13: Ave = 54. 34% will throw 59. 13.6% will throw 64. 2.1% will throw 69. 0.1% will throw 74. 1-in-a-million will throw 79.
Age 14: Ave = 60. 34% will throw 66. 13.6% will throw 72. 2.1% will throw 78. 0.1% will throw 84. 1-in-a-million will throw 90 mph.
I have not researched Axe’s methodology enough to know how accurate these numbers are likely to be; however, I am not particularly surprised by the numbers. They were given to me by someone who is in a position to use them professionally for projecting the future ability of prospects.
Let it be noted that these numbers do not square with what most dads, and most youth pitchers, believe about themselves. In fact, most peoples’ subjective opinion about their son, or themself, appears to bump them up by 5 - 10 mph, almost automatically.
However, these numbers do not refute the possibility of any individual kid being in the 4 or 5 std dev groups–they are like actuarial tables…the numbers merely suggest that there are very, very few individuals in those elite groups.
And, these numbers also suggest (against, for example, common experience on the internet) that there might be some occasional exaggeration of kids’ abilities.
I have had recent occasion to gun (tuning-fork calibrated Stalker 2) quite a few SF Bay Area JUCO pitchers. These are very reasonable JUCO programs, well-known for sending their grads to D1 and D2 4 year colleges and, in a few cases, directly to pro baseball. Somewhat surprisingly, most of these guys are throwing in the mid-to-high 70’s. 80 to 85 is probably the 13.6% bracket for these 18-22 year old guys and 90 is rare, probably 1 or 2% of these guys.
Obviously, the higher up you go…the higher density of velocity-gifted individuals you will find in good programs. On the other hand, each level of baseball has its average velocity, and a bunch of std dev groups below and above the average. To find a home among the average or below-average velocity pitchers at each level of baseball, an emphasis on pitch command, variety, and wisdom may help a lot.