OKLAHOMA CITY — The Warriors took a flyer on Omari Spellman last summer. This week will serve as a performance review of sorts, conducted in public view.

Thursday is the deadline for the Warriors to exercise their option on Spellman’s contract. Spellman is signed through this season, but if the Warriors want to lock him up for next season, they must do so by Oct. 31.

“You’d almost like another month or two to see him in actual games,” Warriors coach Steve Kerr said. “You have 30 days to evaluate a guy then you decide whether or not to pick up his option.”

Whether they will is uncertain. For sure, though, his chances look better than they did in the summer.

In July, a year after using their first-round pick (30th overall) on the Villanova big man, the Atlanta Hawks decided they’d seen enough. They traded Spellman to the Warriors for center Damian Jones and a future second-round pick. He had come to Summer League at 315 pounds.

While the deal for Spellman was primarily a cost-cutting move for the Warriors, the second-year forward had an opportunity to earn a role in training camp. With injuries to Willie Cauley-Stein (foot) and Kevon Looney (hamstring), Spellman started the first game of the preseason. In the four exhibitions, he averaged 4.3 points, 6..5 rebounds, 1.5 assists and 0.5 blocks in 17.1 minutes. His most impressive stat as a Warrior: He has lost more than 40 pounds since the start of camp.

He can feel the difference.

“I’m just quicker, better defensively. When I’m better defensively, we can get out in transition, I can run the floor better and it’s just easier for myself. It makes it easier to score points, protect the rim, and rebound,” Spellman said. “By not having anything on me, it just makes it easier.”

This isn’t the first time Spellman has dealt with weight issues. Spellman, 22, showed up at Villanova weighing nearly 300 pounds. During his redshirt freshman year, with the help of his coaches, he cut 50 pounds and got down to what he considers his ideal playing weight — 245 pounds.

Spellman left college after two years, and the structure he had in place at Villanova was gone. In the NBA, there is help, but there is also freedom. It’s up to players to manage their bodies. With the Hawks, Spellman ballooned back into the 290s.

“Sometimes, I felt like I was a little too comfortable,” Spellman said. “Feeling like ‘I got my money, I arrived.'”

To keep himself in check, Spellman is building his support system. His grandmother and mother flew out to San Francisco to help him move, and he talks to them every day. He’s leaned on forward Draymond Green — who cut 25 pounds right before last season’s playoff run — for advice, and has worked with assistant coach Aaron Miles on fitting into the Warriors’ system.

“We’re trying to get him to understand that ‘You’re a threat. Be a threat,'” Miles said.

Warriors coaches want to see good five-minute stretches from Spellman. They don’t want Spellman to idle on the perimeter, as he did in Atlanta. They want him setting screens, rolling to the rim hard, sprinting back on defense and talking to his teammates. It comes down to conditioning.

“When fatigue sets in for any body,” Miles said, “the mind goes and then the voice is going to leave, too.”

The preseason offered flashes for Spellman, but he ultimately lost status to forward Marquese Chriss. After playing 23 minutes in the first preseason game, Spellman logged 19, nine and 17 minutes in the next three. In the regular-season opener last Thursday, Spellman played 11 minutes, finishing with eight points and five rebounds, most of it in garbage time of a 141-122 loss.

After Sunday’s game at Oklahoma City, Spellman will have only two more auditions — Monday at New Orleans and Wednesday at home against Phoenix. Thursday is D-day.

Even if the Warriors pass on his option, Spellman will have plenty of time to impress them and every other NBA team. He will be a free agent next summer if the Warriors don’t lock him up by Thursday.

“I think I can be a very good player,” Spellman said. “But it’s not really about what I say, it’s about what I do. I want to prove it not only to myself, but to this organization, that I’m worth it.”