I think we need to decide what type of Manager we want first.
Mancini won things with City, albeit perhaps also underachieved, but had seemingly little appetite for managing anything else other than the 1st team and had shown very little interest in their Academy, U21s or structuring the club.
Moyes on the other hand, well, has pretty much played an integral part in overhauling the setup; appointing well respected individuals in the Academy and U21s; people with a similar ethos to himself. You can be sure he took an interest in Academy matters but respected Irvine, Sheedy, Dewsnip and co to come to decisions on their own. When your boss is a grafter, you want to put the work in yourself.
It's not even a bash on Johnny Foreigner either. Martin O'Neil is renowned for not giving two hoots about training sessions and prefers to leave training matters to his assistants, hence why I'd be mortified to even be linked with such a clown!