They were trying to mimic NFL where players have a jersey, and then they can retire a jersey number if a player becomes associated with it. Made viewing the game a little confusing when new players joined the team (or you were watching a team you didn't know all the player on, and were wondering were they played).
Only it was totally random numbering based on the fact the players chose their numbers.. The NFL offers a range to specific positions on the field.. Specifically..
1-9 Quarterbacks and Kickers
10-19 Quarterbacks, Receivers, Tight Ends, and Kickers
20-49 Running Backs and Defensive Backs
50-59 Centers and Linebackers
60-79 Defensive Linemen and Offensive Linemen
80-89 Receivers and Tight Ends (or 40-49 if those ranges are taken)
90-99 Defensive Linemen and Linebackers
So you have an idea of where the person plays based on number AND keep the individuality of the numbers.. This system works I think.. Its how Ocho Cinco can call himself 85 and TO can say he is the only true 81.
Green Bay retired the No4 with Brett Favre and everyone knows a Green Bay No4 is a Favre shirt..