> Organized sport may be used as a less belligerent means of expressing community solidarity and a relatively healthy outlet for rivalries between communities.

Tangentially related to this point, I've often wondered if this is simply a zero-sum game, and the unity you gain through supporting a particular team comes at the cost of disunity with supporters of other teams.

Sports team rivalries produce all kinds of stupidity the world over. People are routinely killed or severely injured simply because of the sports team they support.