Im not referring to their bodies per say, although that can be a concern.
I agree with what you said and think people need to remember that these kids - genetically freakish as they may be - have not been tested properly. They have mostly played against other kids, likely the biggest fish in the pond, and not really been pushed.
When we throw them in first grade, we throw them to the wolves. Those wolves are as freakish as they are, except they are battlehardened men, experienced in the rigours of the game, a lot faster, stronger and fitter then what they are used to and have recieved all manner of training that the kids have not.
Add that to them not being used to the discipline possessed by a professional, whilst still navigating school, relationships, new experiences as they come of age such as increased responsibilities, family, money and freedom... and now fame....its a difficult melting pot.