By 1988, they had become a Western Conference power and gave the Magic Johnson-led Los Angeles Lakers all they could handle in the conference finals, but Lakers were at height of their run, defeating the Mavs on their way to a second consecutive championship.
However, that was the end of their successes for a while, as Roy Tarpley's suspension for drugs as well as the refusal of Adrian Dantley to report to the team after being traded and injuries to key players left the Mavs out of the playoffs. Despite a playoff appearance in 1990, the next few years were horrible for the team, as Tarpley continued to have troubles and was banned for life. The team came close to setting the record for worst record in NBA history two years in a row. Despite having draft picks of Jim Jackson, Jamal Mashburn, and Jason Kidd, they still were unable to find the right chemistry, although they at least climbed out of the bottom of the league.
The 1996?97 season brought a number of changes to the team that formed the foundation of their later success. Michael Finley arrived in a trade with the Phoenix Suns, and Don Nelson was hired as general manager. The additions of Dirk Nowitzki and Steve Nash in 1998 seemed unspectacular at the time, but it was the combination of those two and Finley that propelled the Mavs to their first playoff appearance in eleven years in 2001. The trio formed the nucleus of what was then the best offense in the league, but defense was still the problem as they crashed out of the playoffs that year, as well as the next three.
Nash left for Phoenix at the beginning of the 2004 season, but Dallas was still able to compete thanks to defensive improvements and the increased scoring of Nowitzki. Unfortunately, that year happened to be Nash's breakout year, being named MVP and leading the Suns to finals, defeating the Mavs along the way.
--Wikipedia
