The man-child reference seems to imply a big, strong player that has hit puperty early and can physically dominate players. It's not just that, to dominate you still need some good skill, but the differentiating factor is hitting puberty early. While it can make some players seems like absolute stars in those middle school years, I don't think it serves their development well. Because they start to rely on being able to physically overpower players, bodying them, etc and don't need to focus as much on refining dodging technique, speed development. Then several years later in HS everybody catches up with their growth spurts and playing that game to physically overwhelm doesn't work. Then the players that didn't have the middle school size advantage but have great skills/speed start to outshine. So there is the potential that being big early can hinder players' development ... to their detriment down the road.
