NA and his team watch these kids in training and I believe if they were good enough they would be in squad.
defenders tend to become regulars at a slightly older age than forwards, maybe because a mistake made up front may not be as serious in terms of a result. Other than Mark Wright, Jason Dodd i cannot remember to many other young defenders.
I also think if we had been mid table this season they may have had a better chance, one thing is for sure they will not get a game in the last 3