Theo Robertson was working out in Chicago ahead of the 2010 NBA draft when he realized something was off. Whenever Robertson leaped for rebounds or dunks, he lacked his normal explosiveness.

Shortly after, the former Cal player was in the Bay Area for his school’s end-of-season basketball banquet. Robertson visited his doctor, who told the 6-foot-6 swingman that he needed a third hip surgery to continue his basketball career.

The surgery and rehab would quash any chance of getting drafted that June. Robertson had been receiving interest from NBA and overseas teams, but he decided to retire from basketball instead of pursuing a career that would last a few more years, at best.

That was a tough choice for someone who had yearned to play at his sport’s highest level. But nearly a decade later, as he navigates his first year as a Warriors player development coach, Robertson, 32, is grateful that he still reached the NBA — even if his role is a bit different than he first envisioned.

He has been a driving force behind forward Eric Paschall’s surprising emergence as a Rookie of the Year candidate. Robertson’s ability to relate to players, his basketball IQ and his experience under respected mentors have some in Golden State’s organization believing he could be an NBA head coach someday.

“He’s just got a really mature, wise way about him for such a young guy,” Warriors head coach Steve Kerr said. “As soon as we could get him, we went back and got him. He’s a really good coach and a great addition.”

Robertson — a Golden State video coordinator for the 2015-16 season — returned to the Warriors last summer after stops with the Lakers, Cal and the Pistons. As part of Golden State’s revamped player-development staff, he works closely with Paschall and guard D’Angelo Russell, overseeing their workouts and film study.

In Paschall, Robertson sees a savvy college graduate who was ready when a rash of injuries forced him into a featured role. Paschall, the 41st pick in June’s NBA draft, ranks first among rookies in points scored (393) and is second in scoring (17.1 points per game), third in rebounding (5.3 rebounds per game), third in field-goal percentage (50.7), seventh in free-throw percentage (81.1) and tied for first in minutes per game (31.9).

What most impresses Robertson is Paschall’s ability to learn on the fly and seize any available opportunity. Though Robertson never appeared in an NBA game, he used his perseverance — the same trait that fueled his rise from unheralded recruit to team captain of a Pac-10 championship team — to become a behind-the-scenes asset during the Warriors’ current rebuild.

After his playing career ended in spring 2010, Robertson worked at a 24 Hour Fitness and the Pac-12 Conference offices before he convinced his former Cal coach, Mike Montgomery, to hire him as a graduate manager and, ultimately, the Bears’ director of men’s basketball operations. Intent on carving out a niche in the NBA, Robertson took an internship in September 2014 in the Warriors’ video room.

His work ethic and mastery of basketball’s nuances impressed Kerr, who promoted him to video coordinator the following season. Over the past three years, as Robertson bounced between two other NBA teams and his alma mater, Kerr knew he wanted to work with Robertson again.

Last summer, while on Gregg Popovich’s Team USA staff in Las Vegas, Kerr caught up with ESPN analyst Jeff Van Gundy, head coach of the USA Select Team. When Van Gundy told Kerr that he’d hire Robertson if he got another NBA head-coaching job, Kerr said, “Not if I get him first.”

About a month later, in one of his first days back with the Warriors, Robertson sat down with Paschall. His goal for his rookie season — do anything he needs to get on the floor — seems modest now.

Earlier this week, while in Chicago for the Warriors’ game against the Bulls, Robertson told Paschall about the workouts there nine years ago that led to his early retirement from playing. This story made sense to Paschall, who has known for months that Robertson’s passion for the game had to be rooted in a dream deferred.

“Anyone who plays the game of basketball wants to stay around basketball,” Paschall said. “The big thing I enjoy about him is he loves the game, and you can see that come through in his work.”

Said Robertson: “People ask me all the time whether I regret my decision to quit playing, and I tell them, ‘I’m still in the NBA.’ I have all these resources available to be the very best at my craft. So it’s an incredible privilege. I feel like I still made it.”

Connor Letourneau is a San Francisco Chronicle staff writer. Email: cletourneau@sfchronicle.com Twitter: @Con_Chron