3. Jalen Brunson
It was a comedy of errors that caused the Dallas Mavericks to lose Jalen Brunson after four years. The Naismith Award winner slipped into the second round of the 2018 NBA Draft, which ultimately hurt Dallas. It allowed him to negotiate a contract that made him an unrestricted free agent after four years and left the Mavs with zero control. Mistake number one.
Brunson quickly took over as the backup point guard behind Luka Doncic, but the team was hesitant to play the two guards together. It was not until his fourth season that JB broke into the starting lineup and began to show his superstar potential, but it was too late. The Mavs had failed to lock him into an extension, and they were hamstrung by the CBA in how much they could offer.
Brunson entered free agency after a breakout fourth season, and the Knicks offered a $100 million contract. It was too good to pass up, and the Mavericks lost him for nothing. Fans viewed it as an overpay at the moment, but Brunson averaged 24.0 points, 6.2 assists, and 3.5 rebounds in the following season as he pushed New York into the second round of the playoffs. JB became a star and made the Mavs look even more foolish.
The Dallas Mavericks should have extended Jalen Brunson when they had the chance, but it just did not work out.