4. The 2005-06 San Antonio Spurs
After barely squeaking out a Game 7 win over the Detroit Pistons in the 2005 NBA Finals, the Spurs bolstered their roster by adding two accomplished veterans. Before joining the Spurs, Michael Finley and Nick Van Exel averaged 15.7 and 11.1 points per game in Dallas and Portland, respectively. That only increased the expectations that the Spurs would finally repeat as champs -- and it looked like they would for most of the year.
They won a staggering 63 games and were led by a prime Tim Duncan, Tony Parker, and Manu Ginobili. However, they struggled through a surprisingly tough first-round series against the Sacramento Kings before advancing to the West Semifinals. There, they faced the Dallas Mavericks, who, thanks to weird seeding rules, were the fourth seed despite having the second-best record in the West.
That meant that the Spurs would be forced to go against Dirk Nowitzki and the Mavericks' number one ranked offense earlier in the playoffs. The rest is history. Nowitzki averaged a stellar 27.1 points on 52.7% shooting against the Spurs' number one ranked defense. That, combined with a crushing mistake by Ginobili late in Game 7, ended the Spurs' chances of repeating. I might never get over this one.