San Antonio Spurs Small Forward: Lonnie Walker
Given Lonnie Walker’s likely role as the Spurs' new sixth man next season, I believe that it makes sense for him to be a part of the closing lineup. After all, he’s shown a knack for scoring and playmaking. Therefore, assuming that he’s able to live up to his expanded role next season, he’d add another offensive threat to the lineup.
On the defensive end, Walker has the potential to be an effective defender, particularly when paired with Murray and White. That would provide the Spurs with a trio of interchangeable perimeter defenders, given they all have similar size and length and all are above-average athletes.
Furthermore, with Walker part of the closing lineup, the Spurs could be a serious threat to get out and score in the fastbreak. With scoring, playmaking, shooting, and defensive potential, he could prove to be a dangerous third option.
San Antonio Spurs Power Forward: Keldon Johnson
Most teams tend to play small ball to close out close games and, given his size and strength, Keldon Johnson makes perfect sense as a small-ball power forward. While the Spurs do have other options at the four, including Doug McDermott and Luka Samanic, both have drawbacks that could be exploited in late-game situations.
Johnson, on the other hand, gives the Spurs yet another two-way option. After all, he can knock down open threes, aggressively attack closeouts, score off backdoor cuts and putbacks, and get out in the fastbreak. He can even handle the ball, allowing him to push it in transition or use a ball screen to attack in the halfcourt.
On defense, he’s big and strong enough to defend bigger players while also mobile enough to stay in front of quicker players. Johnson is also a solid rebounder and can also help on the defensive glass, which is especially important for a small-ball four. Overall, he makes perfect sense in the closing lineup.