In the NBA, there are a lot of transactions between players and teams that happen, and there is no way to immediately judge who won a particular acquisition. It takes several years to truly gauge how a trade, signing or draft pick impacted the parties involved.
Being an NBA executive is one of the hardest jobs to do perfectly, and every general manager in the league has made mistakes they wish they could undo. If unprecedented injuries happen, if personalities don’t gel on or off the court, or if player and team potential is otherwise unfulfilled, the blame all rests on the shoulders of the front office.