"David has been with us since he was nine, and I am delighted for him," said Cassell, a month into his new role of developing a parallel City academy in Abu Dhabi, to the Manchester Evening News.
"He is getting better and stronger, and the chance to play and train with world-class players rubs off on any young player who wants to learn.
"David's family are members of the Prestwich and Whitefield branch of the Supporters Club, and he's been on the scene a long time.
"He knows he has a long way to go but he has great movement, good touch and has always been able to score goals. He was always effective at youth level but I am sure he realises he needs more power and strength when you move up to the senior ranks.
"He is a Manchester boy playing for Manchester City, something we set out to do with the Academy when we started 12 years ago."