I had a sprinter last track season, 10th grader. He was pretty fast. Ran 11.48 FAT to win our league finals meet. Ran 23.84 for 200. Split maybe a 54-55 on the 4x4.
Here is the deal. Those 400m splits came with almost zero conditioning. He had hamstring issues coming out of football and his sprint training didn't do a whole lot to help with the problems.
I have him in my P.E. class now as an 11th grader. I had my class run a 1200 hard, just to see where they were fitness wise. This kid smoked everyone (didn't have the distance kids do it), running 4:10 with no warm up and no training since football season ended (even then, they didn't do a ton of running).
My first thought was that if he dedicated some time to some speed endurance, he could be a really solid 400/800 kid. But, in our small school league, he can keep winning the 100 with very little effort.