Management Problems in a football league.

I am currently dealing with a management problem away from work and in my personal life. Me and a bunch of my friends decided to enroll in a flag football league that starts in March. The minimum that is required for each team is 8 people, and the maximum is 16. Getting my friends to want to play for my team was not a problem until recently. Everyone was very excited until I decided to organize the team, by giving each person a position that best suits them. This was a much harder task than I expected. I thought that everyone would cooperate, when in reality almost every single person who I recruited desires to play the position to benefit their own need rather than the team’s need. My friends are asking me if they could play certain positions that they are not good in. I am in a dilemma with this ethics problem. Should I let my friends play whichever position they desire and not succeed as much as a team, or should I assign positions to all my friends which I think best suits them and have the team be more successful. We decided to meet in a park a week from now, and tryout for each position. Hopefully this will put an end to this never ending argument.