I clock speeds for my kid's team. Our team personally has two Jr.s who rarely break 76, and are mostly 72-74. A sophomore who is mostly low 70s up to 78. A senior who will average 75 or so but can touch 81. A sophomore who struggles to break 70, and is a curve ball specialist. A Jr. who is 77-78. And a Jr. who is 79-81 and can touch 83.
Other teams will regularly throw guys at us who are low to mid 70s. We've seen about 6 guys who could get it into the 80s including 3 or 4 who could hump mid to upper 80s. Guys who can fling mid 80s, even low 80s are not a dime-a-dozen in high school.