3. Rod Strickland
A flashy dime-disher, Rod Strickland lit up San Antonio during his brief time with the Spurs. After being traded to San Antonio from the Knicks during the 1989-1990 season it was immediately clear that when he was on, the Spurs had something special in Strickland.
Unfortunately for San Antonio, they never were able to get out of the first round of the playoffs with Strickland as the leader of their offense. This might have shaken their confidence in the long-term viability of having Hot Rod as their floor general and been part of what drove Strickland to sign with the Portland Trail Blazers.
Strickland never was able to lead the Blazers out of the first round either but he sure did put up numbers there and in his next stop in Washington. He led the NBA in assists per game during the 1997-98 season and made his first and only All-NBA team that year as well.
The Spurs weren't struggling at the time. While Hot Rod was leading the NBA in assists the Spurs were drafting Tim Duncan and capturing their first NBA title. But you've got to think they might have been able to nab another one during the three-year span between '99 and 2001 if they'd been able to pair Strickland with Avery Johnson, Duncan, David Robinson, and a young Tony Parker.