23. Kevin Garnett & Paul Pierce to Brooklyn
In 2013, the Brooklyn Nets acquired two aging superstars in what is shaping up to be one of the worst trades of all-time. The Nets, in search of glory, traded their first round picks in 2014, 2016, and 2018 to the Celtics. All of those draft picks netted them a 37-year-old Kevin Garnett, 36-year-old Paul Pierce, and Jason Terry.
The Celtics essentially turned that haul into Jaylen Brown, Jayson Tatum, and Kyrie Irving. After selecting Brown and Tatum with the 3rd overall pick in 2016 and 2017, the Celtics traded the 2018 pick to Cleveland as part of the Irving trade. So not only did the Nets make a bad trade at the time, but they set up a conference rival for greatness while they've been stuck floundering at the bottom of the league.
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