Been thinking about his comments the other day and think there's an element of truth when you consider his Everton managers:
Moyes just didn't play him enough after he recovered from the leg break, pure and simple. Loaned him out twice in his last season when we were so dearth of options at CM.
Martinez allowed him to burst onto the scene but the longer Martinez was here the more Barkley was given absolutely no responsibility off the ball. He was a passenger who just waited for a counter or for us to be in possession at the end of the Martinez era. It was so different from the all action player who looked like a world beater in that first game against Norwich away.
Koeman made him a harder worker off the ball but suppressed his ability to run at and take on players, we did see a bit more of his ability to run games and pull the strings but even then he was often played on one of the wings and Koeman tended to opt for more defensive players in the midfield 3. Koeman's constant scapegoating didn't help things.
As for Allardyce... I'm pretty sure he was briefed the lad was already gone so I can't really comment on that.
Don't get me wrong now Barkley's gone, and the manner in which he jibbed off the club, he can do one. But I think there was something in those "not coached" comments.