Ron Harper Jr. has played more than 10 minutes in an NBA game just eight times in his four-year pro career. Five of those outings have come this month. He’s earned a larger, more consistent role with the Boston Celtics after the team shook up its rotation after the Feb. 5 trade deadline.
While the increase in run may seem circumstantial, it’s not.
“Trust doesn't just come from what you do in the games,” head coach Joe Mazzulla explained at Saturday’s Celtics practice in Santa Monica. “You know, it comes from what you do in workouts. It comes from what you do in the film session. It comes from what you in Maine. It comes what you do on an optional day. If you're working one on one with your coach, like trust happens in so many ways.”
Tuesday’s win over the Phoenix Suns marked Harper Jr.’s second career start. He logged 30 minutes and 17 seconds of playing time, and the Celtics outscored the hosts by 25 with him on the floor.
Typically, fans will look at scoring first, when evaluating a player’s impact on any given night. Harper Jr. did fine in that regard. He tallied eight points on 10 shots, including shooting just 2-7 from three.
The minutes, however, are often the real tell of how well a less-experienced player fared. If an unproven guy isn’t playing well, Mazzulla won’t hesitate to pull them. Of course, that wasn’t the case with the 25-year-old.
“He cares about the details,” Mazzulla praised postgame. “Obviously, the offensive stuff — he can make shots, he can think, he can play. But defensively, just competing, understanding the details, executing the game plan, taking pride in defense… He just loves basketball… Just another guy who — We can count on him… And he’s earning that.”
If you want to talk about taking pride in defense, look no further. Suns players shot a combined 3-12 when Harper Jr. was the primary defender, and the two-way guard finished the game with a steal and a loud block.
Every angle makes it even more impressive 🤯 https://t.co/E23BqHSr1c pic.twitter.com/XpaoZj63Sy
— Boston Celtics (@celtics) February 25, 2026
Ron Harper Jr. helps the Celtics in a multitude of ways
His impact doesn’t stop there, either. Every time he’s gotten the chance, Harper Jr. has hit the glass hard on both ends. In Phoenix, he ripped down four early offensive rebounds while Boston struggled to put the ball in the basket, giving the team crucial extra possessions.
Harper Jr’s rebounding was an eye-opener in his first career start in Houston earlier this month, too. He nearly had a double-double with 11 points and nine rebounds, four of which came on the offensive boards, in Boston’s 114-93 win over the Rockets. The New Jersey native attacks the glass with an extreme motor and high-level of physicality.
“He makes the most of [his minutes], that's for sure, and he fits right in like nothing,” Sam Hauser told reporters in the locker room. “Nothing changes when he gets out there. There's no skipping up the beats. He's a great player. He's a great defender, and he helps us in a lot of different ways. Tonight he was great. Hit some big shots, lot of big rebounds and offensive ends. So credit to him. He's doing an awesome job.”
Fitting seamlessly into the Celtics’ rotation isn’t easy, but it does come as a choice for a lot of these fringe players.
“To me, it's like, Are you showing an attention to detail to the things that we need to do? Are you showing the right mindset, are you showing the ability to execute?” Mazzulla explained Saturday.
Once a player signs in Boston and is put into their development system there, they’re programmed to answer those questions with a resounding “yes.”
There’s also an element of showing up and putting the work in on a daily basis, which Harper Jr. has been doing since the summer, according to Derrick White.
“It's been amazing,” White said of watching Harper Jr. grow comfortable in Boston’s rotation. “I think he really came in this summer [and put in the work], and then when I came back [for training camp], I grew to see how much his confidence grew, and how comfortable he felt out there… Even when he doesn't start, when he gets those minutes, he's done a lot of good things for us. It's great to see, and we're gonna need him for the rest of the year, for sure.”
The opportunity is certainly there for the taking. Since the Celtics flipped Anfernee Simons to the Chicago Bulls for Nikola Vucevic. Harper Jr. has featured in their rotation in all but three games. Because of Harper Jr.’s work, and the way Boston’s internal development staff operates, the team has been able to add another winning player into the mix in the middle of the season.
“Him chipping away at [the little things] and just stacking days together of being really good has put us in position to where [we can trust him],” Mazzulla highlighted. “If he executes something in a game, he's had to go through executing that in a practice, in a film session, and that's [the same] for everybody. So really, he puts his head down and wants to execute, competes at a high level, and you're kind of seeing the benefit today.”