This. Why would players who are good enough to play for a top four club's first team, suddenly be happy with bench roles?
They wouldn't.
I'm in the 'A squad of 15-16 quality players rotating, and backup as youth coming through' Side. You have far less to lose.
Plus if you continually demote first team members for new players, the wage bill is going to go through the roof.
Then how does Fergie get it right year after year?