There is a growing, almost established, trend for AFL clubs to have a 'leadership group'.
I reckon teams are better off just having a captain and a vice captain. The skipper and his deputy should be mature, experienced players of good character who are respected by their peers and who's performances have spoken for themselves over a period of time. Because of this they command respect whether they are playing well or poorly. They have nothing to prove.
As they say "form is temporary, class is permanent".
Other players will have peaks and troughs in their confidence over the course of a season depending on how well they are playing. When they're going through a purple patch of form they will naturally be more vocal and encouraging at training and at team meetings and gee up their team mates. If they're going through a lean patch they will become more quiet and self-centered. Another player in good touch will take up where they left off.
By appointing a pre-determined leadership group, a club is narrowing the focus of the squad and expecting the players to look to the 'leaders' at all times even if some of them are in poor form and subsequently moody, cynical and down on confidence.