4. Boston Celtics acquire Isaiah Thomas at the trade deadline (2015)
When Brad Stevens took over as the Boston Celtics head coach during the summer of 2013, the general consensus was that the team was undergoing a massive rebuild, and that it would be several years (at least) before they would even be a playoff team again, let alone a title contender.
But that all changed at the trade deadline in 2015, when Ainge traded for an undersized point guard named Isaiah Thomas.
In just 2.5 seasons in Boston, Thomas etched his name into Celtic lore. He embraced the role of the underdog, serving as the undersized leader of a team without a true superstar. He embraced the City of Boston and took a rebuilding team near the bottom of the Eastern Conference standings and lead them to three consecutive playoff appearances, including a trip to the Eastern Conference Finals in 2017.
Unfortunately, injuries and the infamous Kyrie Irving trade ended Thomas’s time in Boston far too soon. But he remains beloved in Boston to this day, and his legacy lives on through the young players that he mentored, most notably Jaylen Brown and Marcus Smart.