Sure hope your example is extremely hypothetical ! My son was throwing fastballs @ 78mph summer before 8th Grade and 83mph summer before Freshman year. Only way I know this is, opposing teams had radar on him while he played Summer Rec Ball @ our Summer Home in the Midwest. Son was throwing 88-89mph spring of his Soph year in HS. And there he sat for the next 4 years. Dean Stotz told him on his visit to Stanford in January of Junior year, that most guys with Sons' physique do not mature with their fastball until about 20-21 years of age. So my son asked Coach if he could redshirt. Coach Stotz replied, "Well Son, at $50,000 dollars a year, do you really think Red Shirting is a good idea?" Classic Stotz, I about fell off my chair, it was hard to keep a straight face ! But then Coach told my son, with someone like him, they would wait & wait & wait till the fastball came in. My sons' HS pitching coach, who pitched 8yrs in MLB & also was Pitching Coach for a MLB team in LA, always said, "You can not rush a Fastball, it develops in its own time." As for hitting, my son did well Fresh & Soph year, but HS coach stopped letting him hit Junior year. Fear of injury was the reason given. But hey, guess who won the HomeRun Derby with 14 bombs during the Alumni Game Senior year, even over MLB drafted team mate with 1 year Rookie Ball under his belt. Guess who was belting out 440 foot bombs playing Legion Ball summer before college. That was all done in the name of Fun. As for a pitcher taking reps @ the plate @ a D1 college, only time it happened at Sons' College was when the Head Coach got upset at the poor offense by the Fielders and let only the LHP's take a few Reps in 2 games. Sons' friend hit a Homer, but never got a chance to hit again. Psychological strategy by the Head Coach to motivate the Fielders. It is also very difficult to be a 2 way player in college, not enough time in the day to practice for both & do well in class.
Main point to this long response: Every player develops & matures at different rates & every Coach has a different philosophy for hitting & pitching. These are things that your Son can not control. Advice on this Web sites advocates, "Control what you can, as in Academics & Effort. My advice to you: STOP, right now from looking at others to compare your son against. Nothing good will come of it & it is not fair to your Son or your family to weave this type of distraction into the dynamics of his High School Career. It will steal a lot of joy, both his & yours. Instead, live in the moment & create meaningful memories , life is more enjoyable that way. Let your Son be motivated by his own Self-efficacy.