It's all very interesting, I always contend in lower age sport or athletics time put in pays big dividends, even over raw or innate talent. Of course maturation rate of young athletes is another factor.
I think coaches like Prohaska can definitely assist in bringing out the best potential physically with these young men in high school sport. What you do with a mature or a man whom has reached a ceiling is another question. When talking speed there definitely seems to be a ceiling within in one of us.
Like Al Ko stated, "Not hard to tell who is the fastest kid on the playground is". I ran track and cross country in middle and high school. In middle school I was not really aware how fast I was, it took encouraging from my PE coaches and some fellow classmates. I was a very good Little Leaguer but outside that a skateboarding surfer kid. Speed just wasn't part of much of my game.
It was my dad one day whom bought me a pair of spikes and he worked with me a bit before track tryouts and in a surprise to me really at 100 yards I blew the doors off very kid except one. That kid was Jim Doehring whom went on to put the shot for the US Olympic team in '88 and '92 where he won the Silver Medal. As a middle schooler he was a huge muscle bound kid with thighs larger than my waist. We went head to head for two seasons he edging me in wins barely, many a time we tied. But what was so frustrating for us both is at the end of every race we would clock 1-2/10ths short of the school record which was 10.9, We both had multiple wins at 11.0 yet that sub 11 never materialized for either of us.
In high school Jim went on to field sports as his body became too big to be agile anymore and I went on to run 100, 220, 330 H, 440 and both relays. With my other season sport of cross-country I built great endurance and come track season I put the two together and the 440 became my speciality. In way looking back it was like taking a distance that had a more likely ceiling, the 100 and stretching out to a distance that more training, effort, practice, technique, strategy could make you better than the next guy.
I think when you watch these "speed" sprinters today, its who is feeling their best that particular day. They are within a hair in times and being the healthiest guy that day is a big factor on whom has the highest ceiling and best shot at winning.
If you want to read up on an interesting story regarding this subject look up Russian sprinter Valeriy Borzov technique