I don't get it. Since when being able to play multiple positions is a concern? Phil Jones couldn't progress because of his injury and his rashness, not because he's able to play RB and CM. Did it does the likes of Alaba, Kimmich, Sergi Roberto,... any harm? Being able to play more than one positions is a trait of modern top academy graduates these days, since it increases the chance of you breaking into the first team. Not a coincidence that all of our academy graduates in the first team or whereabouts (Rashford,Lingard,Fosu-Mensah,Lingard,Pereira,Januzaj) have been played in different positions. Their "final position" will be determined by where the team need them the most, not the other way round.