The secret to the Celtics’ Summer League success is one lifelong Celtics fan

LAS VEGAS – Celtics rookie Hugo Gonzalez was in the midst of a frustrating game, filled with missed free throws, out-of-character turnovers, and untimely fouls.

So, Celtics Summer League head coach Matt Reynolds asked him a question:

“Are you having fun?”

Gonzalez, the 19-year-old rookie who to date has spent his entire career playing professional basketball for Real Madrid, was thrown off.

“[I was] like, ‘Yeah, I’m having fun,’” Gonzalez recalled. “And [Reynolds was like], ‘I’m having a lot of fun right now.’”

The light-hearted back-and-forth was meant to remind Gonzalez that when he’s enjoying himself, he’s a better player. That emphasis on joy served as a little bit of a culture shock: “It’s really, really different from what I was used to,” he said.

It’s not just Gonzalez. Over the past few weeks, nearly everyone on the Celtics Summer League roster has observed the culture Reynolds has instilled.

Baylor Scheierman, who is in his second Summer League with Boston, has routinely gushed about the atmosphere Reynolds has fostered en route to a 3-1 record, the Celtics’ best July record in years.

“He’s just done a great job of just creating an environment of joy,” Scheierman said. “I really enjoy having him as a coach.”

For Reynolds, the ability to bring joy to every single practice and game this summer has come naturally.

After all, he’s currently living out a dream

The longtime Celtics assistant — who is typically tasked with in-game reviews and is one of Joe Mazzulla’s trusted confidants — grew up a massive Celtics fan in Lexington, Massachusetts, who had hopes of one day working in sports. He loved Paul Pierce and Kevin Garnett, and the energy at the Garden.

“I remember the day I got the job, it was just like a ‘pinch me’ moment,” Reynolds said. “And since then, every single day I wake up so excited to come here.”

Over the past 12 years with the Celtics, there have been moments when Reynolds simply couldn’t ignore his lifelong fandom. One of those came a few years back, when fellow Celtics assistant coach Sam Cassell brought Paul Pierce to one of Jayson Tatum’s workouts.

“That was my favorite player since he got drafted,” Reynolds said. “I can remember where I was for so many of his iconic performances — the duel with Lebron, the game-winners against the Heat…”

In college, Reynolds was the team manager of Syracuse’s men’s basketball team. After graduating, he volunteered to coach boys basketball at Woburn High School before taking on brief stints assisting the staff of teams at UNC Asheville and Eastern Michigan University.

Then he got an internship that forever changed his life’s trajectory.

In October 2013, the Celtics were in search of a film room intern who could complete the simple but critical task of cutting up game film. Plans with the intern the team initially hired for the position fell through, and time was of the essence.

Reynolds, who had no NBA film room experience, didn’t have a job. But his sister was friends with Brian Adams, who at the time was a video coordinator for the Celtics, and Miller put in a good word.

It worked.

“If the Celtics had more time to hire for the position I ended up getting, I would not have gotten hired,” Reynolds insists almost 12 years later.

It seems like he’s only half-kidding.

But after he was selected, Reynolds was committed to making the most of it, even though the internship centered around a task that he quipped could be accomplished via automatic services today. Slowly, the Celtics’ assistant coaches trusted the then-24-year-old with more responsibilities and challenged him not to complete tasks mindlessly, but instead, to really learn how to watch NBA film.

“The next thing you know, I ended up doing opponent scouts,” Reynolds said.

So, what exactly was responsible for Reynold’s ascent?

Several people around the Celtics organization told me that — in addition to his tireless work ethic, superb communication skills, and jovial demeanor — the veteran Celtics assistant has a photographic memory.

Reynolds opted not to use the word “photographic” when we spoke, but he did admit his memory is a strength. I was able to observe his superb ability to recall information first-hand, in awe as we watched him perfectly recite scrum answers from days prior, as well as details from a casual conversation we had more than a year ago.

“I have a really good memory,” Reynolds said. “It’s something I pride myself in — whether it be the NBA, action movie quotes, whatever it is.”

That gave him a leg up in the film room, where he continued to take on additional responsibilities.

And, he continued to move up.

Ironically, Reynolds actually credits his ability to live in the moment for helping him rise the ranks.

“I appreciated the job I was doing, without having an eye towards, ‘I need to do this in order to expand my profile, or go to a different team or whatever,’” Reynolds said.

In 12 years, Reynolds has coached under three (very different) head coaches. The climb has been steady; he turned a video internship into an assistant video coordinator position, and then eventually dropped the assistant title. In 2019, he was named a special assistant to then-head coach Brad Stevens. For one season, he coached under Ime Udoka.

And, when most of Udoka’s assistants followed him to the Houston Rockets, Reynolds stayed put, becoming one of Mazzulla’s lead assistants, a position he’s held for the past three seasons.

As he’s risen through the coaching ranks, he hasn’t felt inhibited by his lack of previous experience playing competitive basketball, because he knows just how prepared he is.

“Players respect if you know what you’re talking about, and they’ll also respect if you know you shoot it to them straight,” Reynolds said. “[It’s about] honesty and preparation. If I don’t have an answer for something, I have to be humble enough to seek a coach who I trust. But more importantly, be prepared — study the opponent, so that when you’re going to present to your players, you know what you’re talking about.”

Now, for the first time, he is the Celtics’ Summer League head coach, and it all still feels surreal

In the middle of the Celtics’ championship season — about a year and a half ago — Mazzulla informed Reynolds he’d be the Summer League head coach in 2025. And while he didn’t know who’d be on the roster or what kind of schemes the team would prioritize, he started prepping then.

“You kind of have to mentally prepare for the in-game responsibilities you’re gonna have,” Reynolds said.

In Reynold’s debut game as Summer League head coach — a 92-78 victory over the Memphis Grizzlies — more than twenty of his friends and family sat in the Las Vegas stands.

“It kind of became a must-win game,” he told me later in the week.

Reynolds, who as an assistant typicall has an iPad in his hands on the bench, didn’t know what kind of a head coach he would be. He was surprised at just how loud and communicative he was on the sidelines.

“I was yelling a lot,” Reynolds said. “I definitely caught myself being like – I’m really loud right now… sometimes, that’s what the game calls for.”

The Cox Pavilion bleachers, inundated with those closest to him, served as a reminder of the long but steady journey.

“Every Thanksgiving, we cheer to Brian Adams,” Reynolds said in a nod to the mutual friend who helped him land the initial internship.

Less than a week after his head coaching debut, his parents sat courtside for the Celtics’ marquee game against the Los Angeles Lakers at the Thomas and Mack Center, the marquee court of the Las Vegas Summer League.

The 87-78 victory over the Celtics’ historic rival was particularly meaningful.

“When my parents told me they might be coming out to the game, I was like, ‘I’m not gonna stand in your way,’” he said afterward with a smile.

Having his parents in Las Vegas is a full-circle moment; Reynolds always told them he wanted to work in this industry, but he didn’t necessarily know what shape that would take, never mind that he’d one day be a lead coach for the Boston Celtics.

“I made it clear to them that going to all these games was pretty clear – I wanted to work in sports,” he said. “And they were very helpful along the way and helped me make that come true.”

“I’m trying to make them proud.”

Ultimately, Reynolds’ gratitude for the opportunity has rubbed off on his players

He knew he was going to enjoy every moment in Vegas — and he was going to make sure every player did as well.

So, he’s developed inside jokes and references with each player on the roster. Scheierman said he and Reynolds have bonded over their joint love for having fun (Reynolds, after all, is the same Celtics assistant who indulges in trick shots with Derrick White at every practice and shootaround, regardless of circumstance). In Las Vegas, he’s assigned movies for different players on the team to watch.

And rising third-year forward Jordan Walsh, who has had a strong Summer League showing for the Celtics, said that Reynolds’ spirit has energized him. Walsh has known Reynolds as an assistant for the past two years, but he’s taken notice of just how elated he’s been at this Summer League opportunity.

“Usually, he’s not a guy who’s super vocal, or super yelling,” Walsh said. “He’s usually the guy behind the scenes. Seeing how happy he is and excited he is — he’s jumping around screaming. I’ve never heard him scream before, and he’s jumping around and screaming. It lights a fire under me personally.”

The 21-year-old has had his best Summer League yet, averaging 15 points on 46.3% shooting, alongside 38.9% from three.

Photo by John Tlumacki/The Boston Globe via Getty Images

The non-Boston Celtics members of the Summer League roster feel the same: Reynold’s energy has created buy-in. Players who are fighting for their NBA careers aren’t overly worried about their individual performances — instead, they’re working collectively toward winning.

“When your coach is doing that, it’s easy for the players to want to do that,” said Jalen Bridges, one of 8 players not currently slated to be on the Celtics roster next season. “It’s contagious. That energy spreads. You can tell that on the floor – we’re all playing for each other. We’re playing as hard as we can. When your coach brings that energy, it’s really easy to get your team to play hard.”

Reynolds has made sure his emphasis on human connection has extended to each and every guy on the roster — not just the ones currently under contract with the Celtics.

“I care about their experience here,” he said. “I want to make sure that they’re enjoying themselves, even if they’re not playing.”

And, while his detail-oriented preparation and scouting won’t waiver, Reynolds won’t deny the joy he’s felt this week in Las Vegas, nor his deep-rooted connection with the Celtics franchise — one that began decades ago.

“I take a lot of pride in representing this organization,” Reynolds said. “The parts of this team that we need to embody have not changed since the Celtics were founded.”

By the end of our lengthy interview, when I asked Matt what the best part of being an NBA coach was, I knew what his answer would be.

“It’s getting to coach for the Celtics,” he said. “It’s been special to work for this team since I got here. I don’t take a single day for granted.”