In the NBA's free-agency period of 2016, as Kevin Durant left the Oklahoma City Thunder for the team that had beaten them in the Western Conference finals, selecting the Golden State Warriors over the Boston Celtics and other suitors, Al Horford did the opposite. He left the Atlanta Hawks for the team they had discarded in the first round of the playoffs, choosing Boston from a list that also included OKC.
It was a sliding-doors moment that transformed the Warriors into an unstoppable juggernaut and the Celtics into ... well, something better than they were. Asked at Horford's introductory news conference if the signing made Boston a contender, then-general manager Danny Ainge said, "We still have work to do.