MIAMI — Few people know Duncan Robinson better than Cleveland Cavaliers coach John Beilein.

He brought him from Division-III Williams College to Michigan and developed him into a star who nearly led the Wolverines to a national title.

But Wednesday night, Beilein, the Wolverines coach from 2007-19, witnessed how much more his ex-pupil has become with the Miami Heat.

“I’ve heard many times about how Michigan helped develop him, but that young man has developed the last two years with the Miami culture,” Beilein said. “He’s developed his game to a completely different level.”

The Heat have taken the product that emerged from Michigan and refined it.

In one year, Robinson has gone from a G-League prospect to an NBA-caliber player who can threaten to drop double-digit 3-pointers on any given night.

Robinson gave his former coach a demonstration Wednesday night, scoring a career-high 29 points that included nine 3s in Miami’s 124-100 win over the Cavs.

Only 25 players in NBA history have made 10 or more 3s in a game.

Robinson swished what would have been his 10th 3-pointer with 14.2 seconds left, but the shot clock expired before the ball left his hand.

The 6-foot-7 Robinson, who set the G-League record for 3s in a game last season, finished one trifecta shy of the franchise’s single-game record set by Mario Chalmers and Brian Shaw.

“Who’s cheering more, the fans out here or Mario Chalmers?” Heat coach Erik Spoelstra said. “(Chalmers) still gets upset at me to this day for taking him out of that game (where he could have broken the record). In a totally different context, I felt like I was looking at Mike Miller just being in that kind of zone and that kind of size and range with his shooting.”

Beilein took a big chance on him several years ago, and Robinson continues to prove him right.

“His movement without the ball, all the things he does,” Beilein said. “That was like watching family go and destroy you from 3. Part of you hates it, but part of you is like he’s part of our blood.”

Robinson spent his first year as a pro laboring through the long treks back and forth from Sioux Falls, S.D., in the G League to the Heat bench, averaging a mere 10.7 minutes in 15 NBA games his rookie season.

A year later, Robinson has become part of the lifeline feeding the Heat’s remarkable 10-3 start — their best since 2013-14, the final season LeBron James, Dwyane Wade and Chris Bosh were together.

“You couldn’t be happier for a guy like Duncan who puts in the time,” Spoelstra said. “I see it day after day. He has a perseverance about him that he’ll continue to grind and work and know that there’s no guarantees to that. This has been steady improvement over the course of 14-15 months.”

Robinson, an undrafted small forward from York, Maine, is averaging 11.2 points per game — one of seven Heat players scoring in double figures — and his 44.0 3-point percentage ranks third on the team.

“My teammates put me in good situations, and I’m just trying to be aggressive,” Robinson said. “A lot of people believe in me on this staff and on this team.”

Miller shot 41.2 percent and played in 139 games during his three seasons with the Heat (2010-13), two of which ended in championships. Miller started only 21 games during that span.

Robinson has started eight games, including the past six after Justise Winslow suffered a concussion Nov. 5 at Denver, and has a chance to exceed Miller’s total in just one season.

Even before he was inserted into the Heat’s starting lineup, though, Robinson was one of Spoelstra’s early subs off the bench.

He has become a major weapon on a Heat team that continues to lead the NBA in both field goal (48.2) and true shooting percentage (59.4) and ranks second behind the Raptors in 3-point percentage (39.6).

Spoelstra has been impressed with Robinson’s knack for getting hot and hitting multiple 3-pointers in succession, a skill he compared Wednesday to past Heat sharpshooters like Miller, Wayne Ellington and Ray Allen.

“In the preseason, he had two quarters that broke open games when he hit four 3s just like that,” Spoelstra said. “I kept telling him, ‘Build on that. Once your esteem matches your talent for shooting and the confidence your teammates have in you, then you will be able to do things you can’t even imagine.’”

Robinson (far right) shoots over Cavaliers forward Dean Wade during the second half Wednesday night at American Airlines Arena. (Steve Mitchell / USA Today)

Robinson broke Wednesday’s game open, hitting 8-of-10 3-pointers and helping the Heat to a franchise-high 75 points in the first half. They led by as many as 27.

“He plays basketball the right way,” Jimmy Butler said of Robinson. “I knew a little bit about him before he got here, but I did not know he could shoot like that. He’s confident and he’ll let you know. If he doesn’t have your respect, he’s going to earn it.”

Robinson earned the respect of the Heat locker room long before he started raining 3s on NBA courts.

To that end, his teammates kept feeding him the ball late in the game with the Heat leading comfortably to try and get him to the 30-point mark.

“Ever since I’ve been in Miami, it’s been interesting to see who are the ones putting the most work in, who can buy into their role and do all the little things,” Meyers Leonard said. “Duncan has been incredibly consistent at all of it. He’s constantly getting his work in before and after practice. He’s constantly asking me, ‘How can I maintain my diet? How can I maintain my weight throughout the season?’ He’s doing everything right because I think he understands how big of an opportunity this is for him.”

Robinson’s emergence, along with rookies Kendrick Nunn and Tyler Herro, has given the Heat some added scoring to go with Leonard, Goran Dragic and Kelly Olynyk — all of whom are shooting 38.2 percent or better from 3-point range.

The added depth has helped the Heat to their best shooting start since 2015-16 when they ranked fourth in the NBA in field goal percentage. That team went 48-34 and reached the second round of the playoffs.

Dragic noted how having Robinson as an added threat from the perimeter has allowed the team as a whole to better attack defenses in the paint.

“I feel like Duncan’s confidence is way up and you can see that on the floor,” Dragic said “He’s relaxed. The defense cannot relax on him. It keeps a lot of players out of the paint and allows us to create.”

Robinson knows the struggle of being an “under the radar” talent who has to prove himself on the big stage.

At Williams, Robinson was an All-American and led that school to the D-III national title game.

But when he arrived at Michigan, his confidence was shaken after being schooled in a series of one-on-one pickup games with soon-to-be teammates Derrick Walton Jr. and Caris LeVert.

Robinson decided during his redshirt transfer season to study ways to overcome doubt and, while taking a psychology curriculum at Michigan, taught himself not to believe in slumps.

It helped Robinson go on one of the best shooting stretches in school history (he hit nearly 60 percent over a 13-game span) and power Michigan’s run to the 2018 national championship game.

This preseason, though, Robinson dealt with some confidence issues, according to Spoelstra, when he hit shot just 28.2 percent from 3.

“That didn’t even register to me that he was missing in the preseason,” Spoelstra said. “I had the discussion with him about that and I told him, ‘Your head coach isn’t even noticing that. He’s noticing that you broke open two quarters just like that with three or four quick 3s in a row. That’s what I’m noticing. Shooters go through ups and downs, but once you get to that ignitable quality, we can use that.”

Robinson maintains a close relationship with Beilein and caught up with him during the Heat’s two recent games against the Cavaliers as well as during the Summer League. He keeps the lessons learned in mind as he continues his journey toward becoming a consistent NBA performer.

“Him and I go way back, and I’ve always felt like he’s been in my corner and is someone who believed in me before I even believed in myself,” Robinson said. “I don’t know how I’ll ever repay him for that.”

Beilein said: “All of Michigan is proud of him. His family is terrific. He’s had great coaches and has good people in his life, and everyone loves him. It’s great to see.”

(Top photo: Michael Reaves / Getty Images)