the generally accepted systems are different in Italy and England. In england its hugely more common for the manager to choose the transfers. In italy its the sporting director who choose the transfers (other than Mourinho). The SD role in Italy is as much as an art form, a buisness role, a skill, as the manager himself. Galliani always has some credit for Milan's success, as Moggi always had credit, and still does, for our success of the past. Its only started to change slightly in England since the foreign owners came in en masse, bringing not just different managerial styles, but also different managerial setups...Damien Comolli for example.
Hard to say for sure which is the better system, given the success over the years of the italian teams compared to that of the english teams, but i prefer the english model. It simplifies matters, and the Manager truly is the Manager, whereas a manager like delneri, seemed just the head coch, making do with whatever he was given to work with. Conte is a stronger personality, and obviously is working alongside marotta, not below or above him. I suspect that Conte has the final say.