Shawntae Wright knew something was wrong when she saw pictures online two years ago of her son, Marquese Chriss, from a few of his Phoenix Suns games.

Even when Chriss smiled, he had a sadness in his eyes that confirmed what Wright had suspected: Roughly 18 months removed from going No. 8 overall in the 2016 NBA Draft, Chriss was having a tough time, unsure whether he was meant for professional basketball. Wright wanted to board the next flight to Phoenix to help him, but she couldn’t leave her social-work job and 6-year-old son in Sacramento.

These days, Wright seldom misses Chriss’ home games. After finishing work, she makes the 90-minute drive to Chase Center, where Chriss has shed his reputation as a malcontent and emerged as a key reserve for the Warriors. His screen-setting, timely passes, interior defense and highlight-worthy dunks have forced many in Golden State’s organization to view him as a potential franchise building block.

Barely old enough to drink legally, Chriss has just begun to tap into the raw potential that once made him a lottery pick. After trying to become a 3-point threat with Phoenix, Houston and Cleveland, he is now content to focus on his strengths, offering the Warriors an instant-energy big man. Playing the most center of his career, Chriss has posted double-doubles in three of his past five games.

His shooting percentage is up 11.5 points from last season, from 37.2 to 48.7. As guard Damion Lee put it, Chriss is “only 22, and he’s 6-10 with a 40-inch vertical, knows where he is, knows his spots and is finding his way. … He’s been a hell of a force.”

This is quite the turnaround for someone who, after receiving no guaranteed offers in free agency, joined the Warriors in October as a training camp invitee. To earn a spot on the regular-season roster, Chriss had to impress the front office enough for it to waive Alfonzo McKinnie — a rotation player during last spring’s Finals run.

With the Warriors, Chriss has found a coaching staff that tries to maximize his ability instead of harping on his weaknesses. Forward Draymond Green has often reminded Chriss that he was a top-10 pick for a reason. After practices, Chriss challenges Eric Paschall, D’Angelo Russell, Ky Bowman or Omari Spellman — all of whom are within one year of him — to games of “Call of Duty.”

Wright is just happy to see Chriss laughing again. For much of his first three NBA seasons, he was withdrawn, overwhelmed by the weight of expectations. With playing time fleeting and criticism relentless, Chriss began to wonder whether he was a fraud.

“I feel like a different person,” Chriss said. “I didn’t know it at the time, but I was in a really dark spot where it just didn’t feel like this was for me sometimes. Since getting here, I’ve found joy in it again. I’m enjoying the opportunity that I have.”

It doesn’t hurt that his family is a quick drive up I-80. When not on the road with the Warriors, Chriss rarely goes two days without seeing Wright. After nearly a half-decade away from home, including his lone college season at Washington, he appreciates being close enough to visit his parents easily and far enough to feel as though he has some space.

Chriss attended his first family holiday party in years on Saturday. After Wednesday’s Christmas Day game against the Rockets at Chase Center, he’ll host family at his San Francisco apartment for dinner and a contest to see who can make the best gingerbread house.

But first, Chriss hopes to finish unpacking boxes. Finally, he figures, he has found an NBA home.

“Marquese is in a really good place,” Wright said. “You can see it. You look at his pictures, and you see his eyes. His eyes are smiling now.”

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