5. Roy Tarpley
One of the biggest what-ifs in the history of the Dallas Mavericks, Roy Tarpley joined the organization in 1986 as its No. 7 draft choice. It was a match made in heaven as the Mavs needed a backup behind starting big men James Donaldson and Sam Perkins.
The University of Michigan product's skills translated well into the NBA. An impressive rebounder and paint protector, he became a double-double machine off the bench in the four seasons following his rookie campaign, which saw him earn an All-Rookie First-Team selection. For good measure, he also won the Sixth Man of the Year honors in the 1987-88 season.
Unfortunately, Tarpley caused the franchise massive headaches, which may be one of the reasons he is often forgotten when talking about the best prospects to suit up for Dallas.
Trouble started brewing six games into the 1989-90 campaign after he was arrested for driving while intoxicated. To make matters worse, he resisted arrest. His brush with the law resulted in the league suspending him indefinitely. After getting apprehended again for the same offense and violating the Association's drug-use policies in the next few years, Tarpley was handed a lengthy suspension.
He returned in 1994 briefly after a stint in a court-imposed personal aftercare program. Sadly, though, he couldn't stay sober, as another violation had the NBA banning him from the league for life.
If only the New York native played today, the league and the Mavs would have likely been more equipped to handle his addiction.
The late Tarpley finished his NBA career playing just 280 games. However, his career averages of 12.6 points, 10.0 rebounds, and 1.2 blocks per contest underscore how good of a hoopster he could've turned out had he found himself in the right situation, such as the current Mavs probably.