Dwain also gained some significant body weight though too. Remember you have to consider your goals when you are training… if Dwain felt he needed explosiveness in the first 10-20m of his race, then he should be improving his squat… if his times didn’t drop as his squat max improved, then the excess weight he gained outweighed (figuratively) his need for improvement in that area.
Also, until your body becomes upright, your speed is more dependant on quad and push strength… when you’re vertical, it becomes a combination of factors, but definitely more of a pull than a push.
Also, too much air time? I think that must be a Sprint technique error because I doubt anyone has more air time vs gct that bolt and those guys have.