Wieskamp becoming the better player isn't guaranteed for the San Antonio Spurs
To be blunt, I doubt that Wieskamp sees regular minutes in San Antonio this coming season, as I think Austin will be a more likely destination for his rookie season in the NBA. Particularly now that the Spurs made several free agency acquisitions to improve their shooting, Wieskamp can afford to play regular minutes with the Austin Spurs rather than warming the bench in San Antonio.
Coming into his rookie season, Wieskamp is going to have to face some of the same hurdles that Robinson had to at the beginning of his career. Most notably, both players have never been known as elite defenders, and both probably never will be known as such. Wieskamp will be coming into the league weighing only 205 pounds (as of the combine) and will have some issues defending some of the more physical wing players in the league like Kawhi Leonard and Paul George.
If I were forced to nitpick, something else that concerns me about his game a bit is his free-throw shooting. While he was able to shoot 46% on his threes in his final season at Iowa, he's only a career 77% free-throw shooter and had his worst shooting year from the line this past season, only connecting on 68% of his free throws.
Ultimately, his jump shot translating to the NBA will be what determines his effectiveness in the league. If he can become elite in that area of his game like Robinson has, then his development on defense won't matter quite as much. If he can improve his defensive IQ though, Wieskamp has a chance to become a player with some serious long-term staying power in the league for years to come.