I never really understand that particular criticism of Unsworth. There are plenty of valid criticisms (and I do think he had a spell of being far too cautious as a coach with the age profile of the team) but not sure that the idea players arent developing and hes not pushing people up is one.
During the last few years, Davies, Dowell, Kenny, Holgate, DCL, Garbutt, Galloway, Gordon, Browning, Pennington, Baningime, Brainthwaite etc have all made first team starts having spent time in his academy. To varying degrees, all showed promise and in truth most seemed to flat line after being promoted to the 1st team squad.
There are a lot of issues to be discussed as to why, but once a player plays for the 1st team they really have little to do with the 23s. Even if they play the odd game, its seen very much as doing a favour, rather than being part of their squad.
I remember at my semi pro side, we had a lad the year below me as an under 16, he played with us, was great and then trained with us. Quickly he played for the reserves and then wouldnt train with us. I always remember he played the youth cup game, but that was it. When he got an appearance with the 1st team, the reserves didnt see him. Essentially these lads have little to do with Unsworth once they are passed up.