The captain is the person that helps the team communicate and work in an orderly manner, so yes the captain is important in a team's victory. The person that is considered the captain ensures order among the team and he or she is the person the team looks to for guidance. If there is no captain then everyone will be inclined to direct themselves in various directions which in turn damages cohesion and the general well being of the team. A team must be able to work together to play and gain victories.
Captains are nice to maintain the order of a team but they are not important to the teams success. It is a coaches job to make sure that the team runs smoothly and to implement plays, there is no need for a team captain. It is the players that make a team, not a captain.