Why Spurs Have Stephon Castle to Thank for Evening Western Conference Finals vs. Thunder

OKLAHOMA CITY — The Oklahoma City Thunder had already sent the Los Angeles Lakers home in the second round of the NBA Playoffs. But Southern California rapper Thundercat still found a way to claim relevance in the Western Conference Finals.

Late in the third quarter of Game 4 between the reigning champs and the San Antonio Spurs at Frost Bank Center Sunday evening, game officials stepped in to allow for some hardwood cleanup. Nobody moved. There was blood on the floor.

"I would’ve expected it sooner, honestly," Stephon Castle said in the locker room postgame, asked about the heavy splatter. "That’s the kind of series it’s been."

As blood was wiped from the floor, both San Antonio and Oklahoma City prepared for further war. Through four games of the series, four players have sat out with various ailments, 10 have played over 45 minutes in one contest and the series is tied at two wins each.

The Spurs have Castle to thank for his role in their two victories. At the forefront of their defense, the second-year guard has set a tone in stopping one of the league's premier talents.

De'Aaron Fox laid it out behind a microphone after evening the series 2-2.

“We contested 91 percent of shots today," Fox said before moving on to acknowledging Castle. "Our job is to be behind him, helping him. You don't want to play guys one-on-one. That's a tough thing to do ... we just want to give him the help that he needs."

May 24, 2026; San Antonio, Texas, USA; Oklahoma City Thunder guard Shai Gilgeous-Alexander (2) drives the ball in the first quarter against the Oklahoma City Thunder during Game 4 of the Western Conference Finals for the 2026 NBA Playoffs at Frost Bank Center. | Scott Wachter-Imagn Images

Castle, who anchored the Spurs' perimeter push all season, finished the year opposite a sophomore slump. With an increased role next to Fox and rookie Dylan Harper, the 21-year-old averaged 16.7 points, 5.3 rebounds and 7.4 assists on 47 percent shooting from the field.

On defense, Castle forced just over one steal a game while placing the burden of guarding the opposition's best player on himself. It garnered him league-wide praise, though none came as loudly as it did within the walls of San Antonio's locker room.

"(He's) the best perimeter defender in the league, and he holds himself to that standard," Devin Vassell said. "You don't want to get beat up all game ... and that's what Steph does."

Castle's wits were put to the test in the biggest series of his career.

A gruesome battle with the Minnesota Timberwolves revealed to the Spurs that their bold strategy of double-teaming their opponent's most prolific scorer seemed to work well enough in high-stakes situations. Perhaps what went unaccounted for was the biggest difference between the Anthony Edwards-led squad and the Thunder.

Where Minnesota lacked weapons beyond its stars — partly due to Donte DiVincenzo tearing his Achilles in Game 4 of the first round — the Thunder had them in spades. If Gilgeous-Alexander was being doubled, Alex Caruso remained wide open in the corner.

As daunting as a Castle-led double team appears on paper, Gilgeous-Alexander had no issues finding his teammates off the double team. The Thunder's shooters were left wide open on 65 percent of their 3s, and Caruso, who logged just four 15-plus-point outings in the regular season, went for three straight to begin the series.

"They made a lot of shots," Castle admitted. "A lot of them we wanted them to shoot."

The Spurs switched to a more straightforward approach on Gilgeous-Alexander in Game 4, forcing him to play in space and create his own shots over finding an open teammate.

As the first line of defense, Castle got the first crack at the back-to-back MVP. Like he's done all season, the guard welcomed that opportunity.

"One of his best attributes is the fact that he wants to do it first," Fox said of Castle. "That's before we even get to what he can do physically. Just that want to be a defender is 75 percent of the battle ... the mentality that he comes out with ... he's taking on the challenge."

May 24, 2026; San Antonio, Texas, USA; San Antonio Spurs guard Stephon Castle (5) warms up before Game 4 of the Western Conference Finals for the 2026 NBA Playoffs against the Oklahoma City Thunder at Frost Bank Center. | Daniel Dunn-Imagn Images

While Castle wouldn't dare take all of the credit, Gilgeous-Alexander's 19 points marked only the second time all season he's finished below 20. The Thunder was held to 83 points on the evening, and forced the Canadian star to sit the entire fourth quarter. Castle, meanwhile finished with 13 points of his own in the winning effort.

“We’ve got good individual defenders,” Victor Wembanyama said. “When we connect the individual to the team defense, it holds teams to low scoring numbers.”

Added Vassell: "It takes a whole team to try and guard somebody like that."

Asked about the change in defensive scheme, Gilgeous-Alexander couldn't help but give flowers to the team that's given the Thunder its best challenge of the postseason.

“They punched us in our face early," he said. "Two games in a row they've come out (as) he aggressors. Last game, we were able to course-correct. Tonight, we just didn't do so."

Regarding Castle's defense, his job gets significantly easier knowing a 7-foot-4 phenom rests behind him. He's pointed to Wembanyama as a comforting presence since his rookie season. Yet for all the praise he's received, Castle missed out on the league's two All-Defensive squads, earning 46 total points as the first player left out.

"Obviously, it's unfortunate," he said the following morning, "but you've got to look past it."

With his season on the line in Game 4, he successfully did. Castle helped put Gilgeous-Alexander in tough positions offensively all night — if his unusual 19 points were any consolation, Castle would rather compete for a title over individual accolades.

Ever the level-headed enforcer, the Spurs aren't shocked to hear that of the sophomore.

"That's Steph being Steph," Fox said, putting to rest a night marked by bloodshed.

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