My middle school gym teacher once told us, "Throwing a ball fast takes a great deal of athleticism." I always remembered that from 50 years ago. He was ahead of his time. Look at all of the training regimens out there on social media - it can be confusing.
Many big, strong kids can't grasp the fact that the lanky, skinny kid is throwing so much harder than them. It happens often. You can be athletic and not necessarily look "great in your uniform (a scouting measurement, believe it or not)". Conversely, looking great in a uniform, while a sign that a player is strong and fit, doesn't mean that player can get the fastball up to 90 mph.
A high-level fast ball is now the unwritten "badge of honor". This is good and bad. Most discussion on pitching training invariably leads to, first, increasing velocity. Improved mechanics, arm care, and having fun playing the game are also in there up to a point, but the high-level fastball is the mark of success to players, parents, and coaches.
Unfortunately, they are not wrong.
Unfortunate because it gives a pitcher a false sense of success - having a great fastball - when we know, intellectually, that changing speeds and controlling the secondary stuff will give a pitcher more opportunities and success in the long run.
Some bodies are better coordinated than others. I could give many examples, in baseball or any sport, but I would bet you can instantly think of that one kid who has made you say, "How does he throw that hard, he doesn't look like he should?" Coordination can be improved upon; this is the good news. How fast improvement develops is what defines every young pitcher's (and parent's) internal battle - the fight between attaining elite velocity or superior command of all pitches.
Velocity can get them noticed but throwing strikes will keep them on the mound. It is important for pitchers to focus on both, but plan on gradual growth with short term goals along the way. This is where showcases provide value. They show progress over time, making it easier for a coach to sit back, study the data provided, and choose the "prospects" who are showing development by their recorded metrics.
After that it is time to compete. Pitchers now need to go out and win games for your team. Winning pitchers well get the benefit of a scout's positive opinion. Good numbers will get scouts to a ball game. The eye test is the final selling point. A hard thrower who gets pulled early in a game after walking three guys in one inning will likely not leave a good impression. A pitcher who competes and bears down after a couple of hits or a long home run to get out of the inning will leave a good impression.
The human body can only throw so hard for so long. A pitcher should be satisfied to know that he has done everything to attain his maximum effective velocity, but becoming a complete pitcher is what they want to be striving for.
A Division I coach told me, one day while watching a HS prospect, that this kid's velocity was fine, but he was here to see his secondary stuff. That is what will make him a winning pitcher at the Division I level* -the quality of his arsenal.
(*Insert DII and DIII, college baseball is filled with pro prospects at every level)
It is helpful to approach fastball pitching with a 95% mindset. It is humanly impossible to repeat and sustain identical maximum effort with every fastball. Staying in that "just under full throttle" mentality will enable a pitcher to maximize velocity and control over the course of a full game. Closers are more apt to go full steam ahead for short bursts. Even they have trouble maintaining maximum results after pitching back-to-back days. If you keep it at 95%, then those few times when you need to "reach back" for a strike out, you will have 100% in there. It works if you practice this approach.
There is a time to think about improving velocity - it is not during the season. Many college players now take a summer break from playing specifically for velocity building. It is more common now than ever and probably a wise decision for some prospects who need to "open eyes" with better mph and rpm instead of W and L or ERA. This is a case-by-case scenario, however. Some guys need to learn how to compete harder and become a "winning pitcher". They need more game experience rather then training time in the gym. Putting up numbers such as high innings pitched is a sign of strength and durability. Any coach welcomes that kind of pitcher to their staff.
Every pitcher writes their own story - a story that should be filled with a combination of hard work, speed and control and confidence. Keep focused on your personal journey and the results will be all your own. No one can take that away from you. When it's time to train, train hard, when it's time to compete, be the best leader to your teammates you can be. In the long run, pitchers need to pass the "eye test".