When the Nets found Spencer Dinwiddie last December, he was toiling in the developmental league, his confidence bruised and his psyche battered.

Ten months later, he’s grown into a self-assured leader. One who’ll have to step up with the loss of point guard Jeremy Lin, and help D’Angelo Russell shoulder the burden as floor general. Suddenly, Dinwiddie’s shoulders seem up to the task.

“That’s the place where he’s progressed the most. When he first came here he was not a very confident player. He was very unsure. It was one of the things I was very concerned about,” coach Kenny Atkinson said. “You saw the talent, the size, the athleticism, liked the player. But he was very unsure of himself, very hesitant in every sense: defensively, aggressiveness, grit, offensive decision-making.

“I guess it’s just maturity. He feels more comfortable. He’s gotten physically stronger. That’s part of it. You see those muscles bulging out. So I see a much more confident player. Mentally, too, he’s much more sure of himself. If there was one big concern with him in the beginning, that was it. So it’s nice to see that progression.”

That development was underscored Friday. Hours after Lin had season-ending surgery for a ruptured patella tendon, Dinwiddie was a team-high plus-15 to lead the Nets to a home-opening win over the Magic. He had 16 points, five assists, five boards, two steals and just a single turnover in 25 minutes off the bench.

Expect a similar role going forward, starting Sunday against the Hawks.

“He’s earned it,” Atkinson said. “It’s not even training [camp]. He’s earned it … over the whole timeline of his [progression]. There’s a certain trust you have when you see the work he’s put in every day. You feel confident with him out there. We did keep him out there longer than what was planned; it’s because he was playing really well.”

The Nets’ biggest task since inking Dinwiddie last Dec. 8 was getting him to expect to play this well.

It isn’t a shock his ego had been bruised. He’d spent his first two seasons bouncing between the Pistons and the development league, before getting traded to the Bulls in June 2016. Then Chicago waived him, not once but twice. He was with the Windy City in the developmental league when the Nets found him, signed him and nurtured him.

“Definitely. The coaching staff invested a lot of time in my development this summer. I spent a lot of time in Brooklyn working out with them, and I think I’ve made some strides,” said Dinwiddie, still just 24. “When I first got here — because we were 20, 30 games in — I’m learning the system. So you’re not always comfortable telling people what to do, because you’re still learning it yourself.

“Now that I’m comfortable in this system, it’s very easy for me to be like, ‘You go here, you go to this spot. This is the time and score.’ … It’s just being comfortable in the system, and also earning the respect of the guys to be able to tell them.”

Dinwiddie was at the point for the decisive run Friday. He had seven points, three boards, three assists and finished a plus-8 in the fourth quarter — all team-highs.

At 6-foot-6, he’s always had the defensive versatility that prompted the Nets to keep him over Yogi Ferrell. And he’s worked over the summer to improve his jumper. But it’s his confidence and leadership that have truly blossomed.

“The biggest strides in my game that’ve happened between when I arrived and now are just being comfortable in the system and with the coaching staff and their confidence in my being able to go out there and produce,” Dinwiddie said.

With Isaiah Whitehead inactive for the first two games and seemingly out of the rotation, the Nets will need Dinwiddie to keep producing.