But here’s the thing about rivalries: A team’s performance in any single year isn’t supposed to matter. What distinguishes rivalry from competition are the psychological stakes that exist even if one team is undefeated and the other is incompetent. One paper published last month in the Journal of Personality and Social Psychology suggests that rivalries make people behave more recklessly than non-rivalries. The co-authors, Benjamin Converse and David Reinhard, came to their finding after studying rivalry in the NFL, international soccer and even fantasy sports. “You can...