@mirage,
To be clear, my comments were in the context of the uLittle (U6-U10), and early youth stages (under U12). My experience and training has made it clear to me that specialization should not occur until after the first stages of puberty, generally U12 for girls and U14 for boys because puberty is a cruel thing and many a specialist youth player has found themselves out of soccer for lack of Soccer IQ.
The current prevailing wisdom of US Soccer and I agree is that the uLittles should not be playing competitively because adults tend to put winning over development. Once teams start chasing trophies, kids are pigeon holed in positions and few make it out of their hole. This is one of the reasons that sports like Futsal and 5-a-side soccer are good, its forces all the players to become defenders, midfields, forwards, etc.