The Oklahoma City Thunder struggled mightily against the San Antonio Spurs in 2025-26, losing four of their five matchups throughout the regular season.
And while many may try to argue that stars like Victor Wembanyama and De'Aaron Fox were the primary reasons for OKC's woes, the reality is that young guard Stephon Castle is who truly proved to be the main difference-maker.
Castle has had very similar success in this year's postseason, averaging over 19 points and six assists per game while shooting 44.0 percent from deep.
Much of his stellar success from beyond the arc comes from the defense sagging off on the perimeter, a dire mistake OKC also made repeatedly in their past matchups.
Of course, in earlier postseason action, the Spurs' opponents lacked perimeter defenders who could consistently stay in front of him. This left them having to allow Castle to walk into open three-pointers, making them pay.
So, the Thunder need to make a series-altering adjustment against the former Huskie, pressing up on him behind the arc.
They must trust the athleticism and physicality of their historic defensive personnel, especially with Jalen Williams's return.
Thunder must not let Stephon Castle orchestrate offense
Whether it's been due to the game plan or perimeter defenders, Castle has been able to get his game off with ease.
In the playoffs, he has taken 4.0 triples per game at a wide-open look (six or more feet of separation), where he has knocked down 37.5 percent of these shots. Against the Minnesota Timberwolves, Castle left them helpless.
Due to injuries and roster construction, they had no hope of staying in front of him. This led him to shoot 57.1 percent from deep with that space.
With this extra space, Castle is also able to implement his explosive burst and strength to get to the rim at ease, where he has shot 74.0 percent in the playoffs.
Even against the otherworldly talented OKC defense, Castle was left open constantly. This could have been because of the fear of All-Star De'Aaron Fox or the athleticism of rookie Dylan Harper, but either way, it was unquestionably the wrong move.
He was second on the team in wide-open three-point attempts in the season series and shot an astounding 50.0 percent.
This defensive decision must change, and with Castle being prone to a poor shot selection inside the perimeter, it could pay off exponentially.
Stephon Castle's offensive weakness is clear to Thunder
Although he has had a superb playoff run thus far, the Thunder are in a perfect position to spoil it.
Castle has improved at the rim and from deep, but his in-between game has been continuously poor. In this postseason, he has hit just 31.0 percent of his mid-range shots despite being a 70th percentile shooter from the area.
The hyperphysicality of Castle actually leaves him looking for aggressive defenders. This choice left him struggling to get to his shots.
Instead, he'll settle for a low-percentage look, especially around the low block. Now, forcing him into these bad shots is much easier said than done.
Against the Thunder, Castle's drives actually increased by about two per game.
Fortunately, the combination of Chet Holmgren's rim deterrence, OKC's athletic perimeter defenders, and Jalen Williams' excellent help defense means the Thunder have an incredible chance to make Castle uncomfortable.
In Monday's opener, the Thunder's approach to guarding the young guard will greatly determine the outcome of the game, and possibly the series.
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