Rafa has been here 4 seasons. Initially he was blocked from bringing in youth players from abroad by Heighway as Rafa had no jurisdiction over the academy, so let's call it 3 seasons. The young players he has brought in have since helped win the youth cup twice then the reserve league. 2 or 3 are now on the fringes of the first team squad, and both Plessis and Insua have got a couple of first team games recently. Give it time and more will come through, of which maybe a handful will make it.
It is very difficult to get the right player who is still young and raw, so affordable enough for us, yet ready to be blooded full time. Look at Walcott, he's still not first team at Arsenal after a couple of seasons. Are we saying Wenger has no idea how to handle youngsters either?
Rafa spent 11m on Babel and that was the first time he felt the squad was strong enough to make that a priority. Naturally he has been rather inconsistent in his first year adapting. You can only blood one or two at time (see United and Ronaldo, now Nani and Anderson). You also have to look after their physical development, which is different for each player, plus ensure their confidence is not destroyed by playing them too much too early, or in a poor side.
I think we will see if Rafa's eye for a quality young player is good in a couple of years time.