2014: Nikola Jokic over Kyle Anderson with the 29th pick
The 2014 NBA Draft ended up being a bit of a disappointment given the top of the draft, so the Spurs were lucky to get Kyle Anderson. That said, they ended up missing out on the prize of the draft in Nikola Jokic. Jokic was taken 11 spots below Anderson and went on to become a two-time (should've been three-time) MVP. Obviously, no one at the time knew that Jokic would turn into arguably the best player in the NBA.
But still, how insane would it have been for the defending champion Spurs to end up with him? It would have potentially changed the years that followed, with the Spurs still signing LaMarcus Aldridge the following summer, but it would have prevented them from replacing Tim Duncan with Pau Gasol. That might have been enough to keep Kawhi Leonard happy, which would have stopped the team from trading for DeMar DeRozan, Jakob Poeltl, and the pick that became Keldon Johnson.
That trade has ultimately proven to be the gift that keeps on giving, and the Spurs wouldn't have been in position to land the number one pick this year, but they probably wouldn't have to rebuild at all either. Sorry Slow-mo, if the team had nailed every NBA Draft, then they would have ended up with Jokic.