Before you decide on team roles, I would suggest that you gather as a team and decide on what is most important to your team.
List out the objectives for the team and rank them in order. Once you have done this, create a Gantt Chart.
Example Gantt Chart
If you can establish your objectives and then chart where they belong - it is much easier to establish roles. Choosing roles before you decide what your most important objectives are is futile. It can lead to absolute failure - especially if you have a small team.
Breakdown your team's schedule into large bits (pre-season, Build Season, and Competition Season). Then take those and break each down into weeks or days.
Place the objectives into the season that they most naturally lie and then assign stop dates for each objective.
THEN decide on roles as to where each person's talents lie and how often they can meet.
This will allow your entire team to see what is important - who is responsible for which area - and how you can cover for those team members that do not meet the deadlines.
Just my 2 cents.