Does the coach in cricket matter the most ? I don't think so. This is not football where a good coach can change the fortune of the team. Cricket is a different game altogether and a coach cannot make much different to a team.
I think you're wrong. A good coach is always needed in all games to win the matches. To come up with a good strategy against a strong team you need a good coach and captain for the team. There are a lot of things players can learn from these experienced coaches and it will help them then they are under stress.
If i was wrong then why the Bangladesh team was not able to make any significant improvement in their bowling department when they have hired a new good bowling coach ? They lost the two T20s recently.