Good teams succeed not because of innate qualities of team members, but because of how they treat one another. Put differently, the most successful teams have norms that cause everyone to mesh particularly well.
Research shows that the optimum team size is five (actual research is 4.6). Team effectiveness and cohesiveness drop at six. Teams tend to be overstaffed, often because managers don't want to leave anyone out.
The more of a head start your organization gets in developing people individually and as teams, the more difficult it will be for competitors to ever catch up to you.