Chelsea aren't a great example, they loan out about 25 young players a year, very few if any ever make it at the club. When Abramovich hired Frank Arnesen he was seen as the man to bring on the young players, something like £60m later not one academy player had turned out for the first team. Josh McEachren was the first player since John Terry about 10-12 years earlier to come through academy and he hasn't exactly gone on to great things.
It took Chelsea years to get a decent structure in place after their take over, it will quite probably take us the same.
I think Chelsea's model is decent, it's just not utilised correctly.
They produce good players, their loan system works well, they make a lot of money but the final piece of the jigsaw is the short termism of their managerial appointments. There is no incentive for managers to take a chance on young players when they know they'll be binned off if immediate results aren't forthcoming. They might have stumbled upon a way forward with Lampard and the current transfer ban but it remains to be see if they have any more patience once that washes through.