What is the proper way to run for speed? (Baseball)?

My son (12) is a baseball player, and he runs SO differently than every other child. I watched 60 kids run a timed 90 feet this weekend, most had medium to long strides and their legs moved fairly quickly. My son has a short little stride, not much of a stride at all, I might call it a studder step and his legs move up and down SO fast, but doesn't your momentum stop each time your foot hits the ground? I am not exaggerating that his foot hit the ground 2-3 times more than every other child there. He ran the 90 feet at 4.50 seconds, while the fastest child ran 3.63 seconds. My son wasn't the slowest, but his run looked SO very different than everyone else s.

What is the proper way to run for speed when dealing with baseball?