4. Steve Nash signs with the Phoenix Suns (2004)
Despite back-to-back All Star appearances, and back-to-back seasons with 52 or more wins, Dallas Mavericks owner Mark Cuban was reluctant to sign Steve Nash to a long-term contract extension. Cuban didn’t want to pay Nash — who was already 30 years old — a lot of money, especially when he was already paying nearly $50 million in combined salaries to Samaki Walker, Michael Finley, Antawn Jamison, and franchise cornerstone Dirk Nowitzki. Cuban’s decision turned out to be one of the biggest blunders in NBA history, as Nash went on to win back-to-back MVP awards in his second and third seasons after leaving Dallas.