Erm... yeah? :?
Prime example: N'Zogbia. Has an unbelievable season last season, now needs a good manager and coach to bring him on, and bump him to the next level of playing ability. He can't do it all by himself because he is a young man. Milner is another example. And Taylor. And Ramage. And Martins, etc.
Look at Arsene Wenger - the 18-year-olds he has in his squad will all develop into brilliant players. Just like Taylor and Ramage and Zoggy would do under him, because he is a brilliant coach.
Roeder's a bad manager, so our players won't improve very much under him.
QIA
I have lost count of the number of people who I have talked to who seem to think that players are 100% responsible for all thier improvement and that the coaching has no effect on thier game. They think they are 'professional footballers' so they should automatically know everything about the game, positioning tactics ect.