Many youth football coaches come into a team with a preconcieved notion of the type of defensive scheme they are going to run.
They do so without even knowing the type of talent they are going to have or the rules of the youth football league they will coach in.
Some things to consider first:
What type of talent do you have: Do you have 4 good linebackers and 2 good rush ends to run the 4-4?
What type of Youth Football offenses will you have to defend against in this league ? Is it a heavy option or spread league?
What are the special rules of this youth football league? Are there minimum play rules that require you to play weaker players on defense? If so, will your defense be able to accomodate weaker players, where do you put them in your chosen scheme?
Are there special league rules that do not allow you to play players in certain gaps etc ?
The answer for most is you have an ideal youth football defense, then you have a defense that can accomodate the players you have, the offenses you have to stop, while living within the constraints of the special rules or minimum play requirements of your particular league.
We don’t have the luxury of running our favorite defense, but we run one that does the best job with the contraints listed above. Thats something that those that have been coaching youth football for a few years understand and where some very sharp hot shots fail.