There are points were it has happened. I remember losing 2-3 to blackburn in the first game of 2008/09 with a 17 year old Rodwell starting, Baxter coming off the bench and likes of agard, wallace, juctkiewitz, gosling & kissock on the bench! Throw in Anichebe & Vaughan who got thrown in a few years earlier than thats a fair amount.
I also remember around the end of the 96/97 season the likes of richard dunne, michael ball, john hills, gavin mccann, danny cadamateri all being thrown into the team.
It has happened before, wether its succesful is another debate