12. Dennis Rodman
This is one of the best players on this list, but his time in Dallas was extremely forgettable.
Most Mavs fans don't even know that he was ever on the team.
The Mavs signed Dennis Rodman in February of 2000 after he had been out of the NBA since April of 1999. Rodman finished the previous season with the Los Angeles Lakers and signed with the Mavs after owner Mark Cuban pursued him.
Rodman was a 5-time NBA Champion and 2-time NBA Defensive Player of the Year heading into his time in Dallas, but his performance as a Mav was not great.
Rodman only played in 12 games as a Maverick and averaged 2.8 points and 14.3 rebounds per game. Obviously, the rebounding numbers were still great, as Rodman is one of the best rebounders of all time, but his field goal percentage was way down at 38.7 percent.
He wasn't great on the court, but his actions off the court were worse. Rodman openly roasted his teammates, and the Mavs released him after just a few weeks. After Rodman left, the Mavs went on a tear and ended up winning 15 of their last 20 games.
Rodman was never a great fit on the Mavs, and he will be remembered for his six techincals and two ejections as a member of the Mavs rather than helping his team.