Think of Barkley's slow introduction from a business standpoint.
Already 6-12 months before his first team debut, we had been hearing about his progression, i remember Cahill citing him as one of the best talents to come through the Everton academy some time back. The preseason and start of season games are to show that he is definetly capable and exciting, though maybe not entirely ready. Lads' gotta be ready when the big challenges come along.
Rodwell is a good model example to portray the pressures of living up to the initial impression. In the summer of 2010 we were all on about £25 mill bids from man u, but after the bad form the team (and him) have been in since, those expectations have been scaled down a bit. Though that doesn't mean he hasn't learned and grown as a footballer. He's earned caps for England and proven himself as a solid player, which is a big step to take. Cause after all, when you play the week-in week-out game and wish to stay there, you gotta substitute that initial excitement for whatever reputation or personality you develop as a player, and the byproduct of this is usually a sort of disappointment. Remember how awesome Walcott seemed at first, and how there suddenly came a time later where everybody seemed to dislike him? Now he still is a regular PL performer, 22 of age, and achieving that is a lot of work in itself.
Stepping up to that level is what Barkley is about to do now, and we would all like to see him start with a bang, come on all exciting and awesome and man-of-the-match-winning like, and just not stop getting better, till he's captaining the team age 21 and scoring (bainesy-assisted) hattricks for England at the world cup. Obviously the initial momentum of his introduction will slow down.
What Moyes is doing now is letting that momentum build without putting too much pressure on him. How well he does also has a lot to do with how the whole team plays - even though we imagine he could come on and save our dire, uncreative side in the middle of a game we're trailing at blackburn away, that might not be the case and disappointment + a lower market value is the result.
I'm glad it's being almost announced like this instead, it shows we have a plan for the kid that he also knows to play by. It's a good as indication of Barkley being ready as any. It's just up to him if he makes it when the time comes.