Devin Vassell needs to show out during training camp to make his case
Vassell has already had a chance to showcase that readiness earlier in the summer when he played in Summer League. He impressed in his outings there, averaging 16.5 points, 5.2 rebounds, and 1 steal in just 22.7 minutes per game. Soon, he'll have the chance to build on that performance with a strong training camp, where he could prove himself as the best option for the vacant starting role.
The team has other candidates for the open role, however, including Lonnie Walker IV and Doug McDermott. Both have more experience, which may initially give them an advantage, but can use the preseason to impress the coaching staff in scrimmages and beat them out for that starting role.
Of course, this assumes that Walker's role isn't already set in stone as the team's sixth man, given his ability to score and his potential as a shot creator. Similarly, while McDermott's elite shooting could come in handy in the starting lineup, he's historically come off the bench and may continue to do so in light of his subpar defense.
That leaves Vassell as a realistic option. While it may seem a bit soon to have him start, Murray, White, and Johnson were all full-time starters by their second season, proving that it's within the realm of possibility for the young 2020 first-rounder.
Moreover, Murray and White were selected 29th overall whereas Vassell was taken in the lottery. This suggests that the Spurs' front office believes that Vassell is the more talented player compared to Murray and White at similar points in their careers. If those two managed to enter the starting lineup by year two, then it may be even more likely that Vassell does the same.