Watch runners like Lagat or Kipchoge and tell me form doesn't matter -- it clearly does, and can make a significant difference in speed and efficiency. I agree Hunter seems to have some side motion that looks like it's fighting his forward motion.
Watch videos of Lagat running the 1500 or 5000. You could practically put a glass of water on his head and it wouldn't fall off. Lagat must have strong hip flexors, as well as flexibility from his feet right up through his back.
Kipchoge shows how form efficiency maximizes speed in the marathon. Arms tucked-in, open hands coming right up to the middle of his sternum. By contrast, Farah still runs with that loping, reaching stride that is just not efficient over the marathon.
Hunter should get measured at one of the facilities that can show how he moves running at speed. They will place sensors on the feet, knees, hips, shoulders, elbows, and head. He should make Adidas pay for it.