He was just simply one of the most capped and trusted player of the team leading him to the role.
The All Whites
Any player, playing in any position can be the captain of a soccer team.
The current captain of French Soccer team is Samir Nasr
The current captain (2008) is Daniel Vettori.
Forward, Claudio Pizarro, is the captain of the men's Peruvian soccer team.
The nickname for New Zealand's national soccer teams is "The Kiwis".
Benji Marshall is the captain of the NZ Rugby League team (2010).
YOU HAVE TO HAVE AUTHORITY OVER THE TEAM
Auckland City, and NZ national team.