3. Montrezl Harrell, Washington Wizards
While he'd be a longshot option, there's no doubt Montrezl Harrell would be a big backup center upgrade over the Spurs' current options. The 27-year-old is having one of the best seasons of his career with the Washington Wizards, averaging 14.9 points and 7.9 rebounds per game coming off the bench.
If you watch just five minutes of Harrell, you can easily see what he's all about. He's going to crash the glass on both ends, do dirt work down low, come up with putbacks, and scream and shout while doing all of the above.
Harrell was the NBA Sixth Man of the Year in 2019-20 with the Clippers and is playing at that level once again with his endless energy.
Where the Spurs might hesitate with Montrezl is his 6-7 height, especially since they already aren't that big to begin with. Still, it's hard to argue with his production. He could be an option to play alongside someone like Zach Collins or Jock Landale off the bench, even sharing some court time with Poeltl.
With Harrell's unrestricted status, there's a decent chance someone might want to pay him beyond what the Wizards might want to match, especially since their resources are limited due to the CBA limiting how much they'll be able to spend.