As a coach, I would look for particular gifts or abilities in an athlete and then carefully consider how they would best contribute to the success of the whole. All are welcome and many have gifts and abilities that only become clear after significant effort and training. Some start out completely different than they end up, to be sure. Some have obvious skills, but many are truly pleasant surprises for me as they develop through hard work.
As the initial disciples were chosen, it is easy to see which roles might have been assigned to each, based on how we can see their personalities and gifts expressed in the Scripture.