Question can go a few ways, one way is: who is the player who was the least good over their careers but will definitely have their jersey retired by one franchise upon retirement?
Alternatively it could be who was the player who accomplished the least but will still get their jersey retired, in which case the answer could be John Wall (“in the league” is being generous to him) A bona-fide Wizards legend with multiple allstar appearances and a handful of All-NBA selections who (along with Beal) carried the franchise through some pretty grim seasons but only ever accomplished a couple of second round appearances