A few years ago, the 92 MPSC Boys team had two coaches who said very little during matches, but I believe that was just their personal style. At the time, I remember being impressed by this. The way I saw it was that these guys had done their job so well during the week that they did not need to yell instructions during games.
I believe that a coach can be successful without saying much during games, but it really depends on the chemistry between that coach and his/her players. For some teams, I think it's necessary for the coach to shout instructions.
Basically, I believe there should be no blanket rule covering this. If you hire a coach, let him/her coach the way they know how.
