Changing the coaching staff will not change anything. Right now, Brazil simply does not have a good squad and there is no one outside of the team who either could do better or has the experience to play in a world level. People can talk all they want about integrating young players from the youth categories, but 1) none of them have the star power as Egonu and Boskovic, for example; 2) Brazil is not known for skipping age categories like most teams are doing these days.
Also, it is always good to remember that Zé is a 3 TIME Olympic gold medalist. Like it or not, the guy knows what he is doing.