Patrice Jones of the Chicago Tribune interviews Northwestern University physicist Luis Amaral (no relation to Rich Amaral I believe) about how baseball teams can be good examples of a complex system.
What are complex systems?
Complex systems are things you cannot break into smaller parts hoping to understand the whole. For example, you can know the names and histories and statistics of individual players on a baseball team, but you don't know whether that team will have a good season or not. That is a complex system. It is when the whole ends up being much more than the individual parts. The White Sox, for example, did not have such an amazing set of individual players [when they won the World Series last year], but they had an amazing baseball team.
So a baseball team is an example of a complex system?
Yes. The  White Sox was really a good example of a complex system in that the whole -- meaning the team -- was bigger than its parts. It is the interplay among the individual players that makes a team into something that could not be understood if we looked at each person in isolation.