Has any franchise been the victim of worse misfortune than the Boston Celtics, post the 1986 Title ?
Well, it depends on how you define it of course.
In terms of squandered potential, probably not (most teams don't have talented draft picks die), but in terms of success, you have the Clippers, Grizzlies, Hornets, Jazz, Magic, Nets, Pacers, Pelicans, Suns and Timberwolves who are still waiting to win it all. The 76ers spent years in the gutter after blowing up a second-round team to get back to the second round. The Knicks have mostly been rubbish since their win in the 70s, and so on.
Not talking about underachieving, performance-wise.
I'm referring to bad luck befallen a franchise that is out of their control ............. like Bird ruining his back because he insisted on doing work on mom's driveway rather than hiring a crew for the job, Len Bias, Reggie Lewis, zero league compensation because Stern hated Red, Garnett's knee injury when the team was on the cusp of multiple titles, Perk's game 6 knee injury with the Celts one game (then one quarter) from a title, taking great care keeping Porzingis healthy all year during the regular season only to have him injured in the playoffs.