In 2011 I was the PM for the team that powered the Google+ social graph (such as it was.) In this session, we will post-mortem a previously untold incident, in which my team developed a new algorithm for suggesting friends, which we had hoped would catapult the social network on a new trajectory to success. We soon found out, in the middle of the night, that we had miscalculated badly. We will learn how optimizing for the wrong metric can spell doom even if the engineering is flawless.