I feel like the "mojo" of developing players is disappearing aswell. Yes, Bellerín, Coquelin and Iwobi (to an extent, he is far from proven yet) progressed into the 1st team recently.
But the likes of Chambers, Gabriel, Wilshere, Ox, Gnabry, Szczesny haven't really developed as expected, the likes of Gibbs, Walcott and Welbeck have regressed and there is a lot of uncertainity around some players - Akpom, Campbell, Jenkinson, Sanogo, or in the past Afobe who made it into PL 1 year after we sold him.
First two groups are especially concerning, players with lot of talent not being developed properly.