Rockets guard Amen Thompson's rookie extension can serve as a reference template for the San Antonio Spurs' contract extension negotiations with Stephon Castle. Thompson has just signed a five-year, $208 million extension with the Rockets, with the salary accounting for 22% of the salary cap.

Thompson has shown tremendous potential, but he still has many weaknesses on offense, making the contract a reasonable one for the Rockets. Frankly speaking, Castle's overall ability on both ends of the floor is even stronger than Thompson's, but his offensive ceiling has not yet been fully realized.
When Castle entered the league from the University of Connecticut, the biggest concern surrounding him was his inconsistent shooting. Although there have already been many positive signs, he still has a long way to go before becoming a reliable shooter.
Many Spurs fans hope that Dylan Harper and Castle can both receive full max contracts worth 25% of the salary cap. If Castle makes the All-Star team next season, a max contract would indeed be deserved.

Last season, the Spurs won 62 games and reached the NBA Finals, with Castle already considered the team's second-most important player, giving his résumé significant value. However, if he fails to make the All-Star team or an All-NBA team next season, the Spurs will face a difficult situation in extension negotiations.
Wembanyama has already signed a supermax extension worth 30% of the salary cap, leaving the Spurs with some room for salary-cap management. But if Castle cannot perform at the level expected of the team's third core player next season, the Spurs should not immediately offer him a full max contract at 25% of the cap.
The Spurs still have about a year to negotiate and hope Castle will follow Wembanyama's example by accepting a contract below the full max. San Antonio may not ask him to accept only 22% of the cap, but if they can persuade him to take 24% instead of the full 25% max, the team could save about $1.75 million per year.

Looking only at the number, $1.75 million is not a huge amount, but this difference could determine whether the Spurs cross the restrictive second tax apron or remain below the threshold. Once a team crosses the second tax apron, it loses many roster-building tools, including the mid-level exception and trade aggregation options, severely limiting roster flexibility.
If Castle makes a concession, the Spurs could later try to persuade Dylan Harper to do the same. Together, the young core could save San Antonio about $8 million per year.
By comparison, the Oklahoma City Thunder already have three core players taking up 85% of the salary cap. If the Spurs can convince Castle and Harper to accept discounted contracts, they would gain a competitive advantage in the arms race, and Amen Thompson's extension at 22% of the salary cap provides an existing reference model.