‘He’s In A Groove’: Dallas Mavericks’ Slide Continues As Boston Celtics Pull Away Despite Cooper Flagg’s Latest Surge
With less than 48 hours remaining before the NBA trade deadline, the Dallas Mavericks took the floor Tuesday night already stretched thin. Injuries had pared down the rotation, trade chatter hovered in the background, and a four-game losing streak had tightened the margin for error.
Through it all, Cooper Flagg kept producing at a level that continues to defy the usual rookie timeline.
Flagg poured in 36 points with nine rebounds, six assists, and two blocks, becoming the first teenager in NBA history to record three consecutive 30-point games. The performance, however, came in another losing effort as Jaylen Brown scored 33 points with 11 rebounds to lead the Boston Celtics to a 110-100 win at American Airlines Center, extending Dallas’ season-worst losing streak to five games.
The Mavericks fell to 19-31 at the 50-game mark. Boston improved to 32-18.
Dallas Mavericks Enter the Night Already Short-Handed
The Mavericks were undermanned before tipoff.
D’Angelo Russell and Brandon Williams were both ruled out on the updated injury report. Russell was sidelined due to illness after being downgraded earlier in the day and did not attend morning shootaround. Williams missed the game with a right lower leg contusion after exiting Saturday’s loss in Houston following a collision.
Russell has appeared in 26 games this season, averaging 10.2 points, 4.0 assists and 2.3 rebounds in 19.0 minutes per game while shooting 40.5% from the field and 29.5% from three-point range. He has played just once in 2026, logging 18 minutes in a Jan. 10 loss at Chicago, and has not logged 20 or more minutes since Nov. 19 against the Knicks, when he scored 23 points in 24 minutes.
Williams’ absence was felt immediately. In Houston, he scored the final 10 points of the first quarter before leaving the game — a stretch that highlighted his importance as a pace-setter.
“B Will is a spark plug,” Flagg said previously. “That’s what he’s been all year for us. He comes in, brings energy, helps get our pace going. His speed, getting downhill, making plays for others — just his energy all around is something we missed, especially there in the middle of the third quarter.”
Daniel Gafford echoed that assessment.
“He was attacking the basket, getting downhill, facilitating the offense, and knocking down shots,” Gafford said. “He’s one of those guys who can get frustrated if shots aren’t falling, but tonight he was ready for those moments. It just sucks to see how he went down.”
Williams has averaged 12.6 points, 3.6 assists and 2.9 rebounds in 21.9 minutes across 43 games this season while shooting 46.2% from the field with a 55.3% true shooting percentage.
Russell and Williams joined an already lengthy list of unavailable players: Anthony Davis (left finger sprain), Kyrie Irving (left knee surgery), Dereck Lively II (right foot surgery), Danté Exum (right knee surgery) and P.J. Washington (concussion protocol).
Early Energy, Then the Same Costly Stretch
Despite the depleted lineup, Dallas opened the game with purpose. Flagg attacked downhill early, mixed in perimeter looks, and helped the Mavericks stay competitive through the opening quarter.
Boston steadied itself behind Brown, who hit a tying 3-pointer midway through the first quarter and followed it with another from deep moments later. From that point forward, the Celtics did not trail again, closing the quarter ahead 32-29.
The game turned in the second quarter, and Mavericks head coach Jason Kidd pointed directly to that stretch afterward.
“Yeah, I think when you look at just some of the stretches where we can’t score, that second quarter was a little tough for us,” Kidd said. “But our defense kept us in it, only allowing 20 points, and we only scored 15. There’s a stretch where we’re down 13 and all of a sudden, in less than two minutes, we’re down 19.”
Dallas briefly trimmed a 50-36 deficit to 52-44 before halftime, but the underlying issue — prolonged scoring droughts — lingered.
“We know they’re going to shoot a lot of threes,” Kidd said. “We’ve got to rebound the ball, and we just didn’t do that well tonight.”
Third-Quarter Run Ends Any Margin for Error
Any hope of a reset after halftime faded quickly, and the third quarter ultimately became the clearest separator of the night. Boston emerged from the locker room with sharper pace and intent, pushing the ball off misses, flattening Dallas’ defensive shell and repeatedly forcing the Mavericks into long closeouts.
Dallas struggled to generate clean offense early in the half, and each empty possession compounded the pressure on a lineup already stretched thin. Boston capitalized by spacing the floor and hunting rhythm 3-point looks, gradually turning a manageable deficit into a decisive one.
The defining sequence came late in the period when Luka Garza flipped the game from control to command. Coming off the bench, Garza drilled three consecutive 3-pointers in rapid succession, accounting for nine straight Boston points during a 14-4 run. The burst pushed the Celtics’ lead to 86-67 entering the fourth quarter and drained what little margin for error Dallas had left.
Garza finished the night 4-of-4 from beyond the arc, scoring 16 points in just 20 minutes — production that underscored how thin the Mavericks’ defensive rotations became as the game wore on.
“We know they’re going to shoot a lot of threes,” Kidd said. “We’ve got to rebound the ball, and we just didn’t do that well tonight.”
That stretch reflected a recurring theme for Dallas. Missed shots on one end turned into early offense for Boston on the other, and second-chance opportunities further tilted the possession battle. Even as Flagg continued to attack and keep pressure on the rim, the Mavericks were forced to play uphill basketball.
Boston’s lead eventually ballooned to 23 in the second half, effectively ending any real threat. Dallas continued to compete late — outscoring the Celtics 33-24 in the fourth quarter — but the damage had already been done. The third quarter, once again, proved decisive.
Daniel Gafford Goes Down — Then Comes Back
Late in the second quarter, Dallas briefly held its breath when Daniel Gafford went down holding his right ankle — the same injury that has already sidelined him for 16 games this season.
The sequence unfolded on the defensive end. As Gafford rotated to contest a drive, his right leg made contact with a Celtics player, causing his ankle to turn awkwardly. He went down immediately, grabbing at the ankle as play stopped, and headed to the locker room shortly thereafter. Given Gafford’s history with the injury, the moment carried added concern for a Mavericks team already stretched thin in the frontcourt.
The ankle has been a recurring issue for Gafford since the first day of training camp, when he initially sprained it. He has aggravated the injury multiple times over the course of the season, most recently exiting a Jan. 14 game, and Tuesday’s scare marked yet another interruption tied to the lingering problem.
Despite the setback, Gafford returned to the floor late in the third quarter. He fought through the discomfort and finished with 10 points and 12 rebounds, providing one of the few stabilizing presences on the night even as Dallas fell 110-100.
Kidd praised Gafford’s ability to return, noting how uncommon it has been this season.
“Yeah, I think it was huge for the team and for us — and for him to be able to come back,” Kidd said. “Normally, he doesn’t. For him to come back after halftime was very impressive. We need all the bodies we can get.”
Gafford has previously spoken about the balancing act required to manage the injury while trying to remain available for his team.
“It’s a bit of a balanced scale,” Gafford said earlier this season. “I want to be out there on the floor as much as I can. But at the same time, you have to listen to your body, especially through the course of a season.
“I just want to come back and be able to do the things I’m able to do out there on the floor and make an impact. I don’t want to be out there being a liability and hurting the team more than helping them.”
Whether Tuesday’s aggravation leads to additional missed time remains to be seen, but Gafford’s return — however brief — was a rare positive for a Mavericks team navigating injuries, losses and mounting pressure as the season wears on.
Cooper Flagg Continues to Redefine the Timeline
Even as the losses mount, Flagg has become the Mavericks’ constant — a nightly through line of production, poise and rapid growth that continues to outpace the typical rookie arc.
The 19-year-old finished with 36 points, nine rebounds and six assists, becoming the first teenager in NBA history to record three consecutive 30-point games. The performance came just five nights after he set the NBA scoring record for the under-20 age group with a 49-point outburst against Charlotte, further underscoring how quickly his offensive ceiling is rising.
“In the last three he’s averaging almost 40 points,” coach Jason Kidd said. “He’s in a groove. He’s scoring the ball, he’s attacking, he’s making plays for his teammates. We’re just not shooting the ball straight. We’re getting some great looks that just haven’t gone down for us.”
Flagg pointed to confidence and pace as the foundation of the surge, emphasizing that the game has begun to slow in meaningful ways.
“Just being confident, being aggressive, getting to my spots, playing with good pace,” Flagg said. “It’s worked out well.”
That comfort has shown up not only in his scoring, but in how he reads coverage. Teams have begun mixing in different looks — going under screens, shading him in certain directions — and Flagg has adjusted in real time.
“That’s part of the game slowing down,” he said. “Getting to your spots, being confident and comfortable, and knowing what shots you want to get to.”
The recent stretch has also quieted earlier-season talk of a so-called “rookie wall,” something Flagg said he never allowed to seep into his approach.
“I’m just proud of myself for staying confident and staying poised,” he said. “I never doubted myself or fell into what everybody was saying about a ‘rookie wall’ or whatever. I just let all that pass. I might’ve fallen down a little bit, but I got back up stronger.”
While Flagg’s individual growth has been undeniable, the context around it remains incomplete. Injuries have prevented Dallas from seeing its roster at full strength, limiting Flagg’s opportunities to build sustained chemistry with the team’s top veterans.
Asked about that, Flagg didn’t hesitate.
“I would love to share the court with both of them at the same time,” he said, referencing Davis and Irving. “I got to play with AD when he was healthy and loved playing with him. Hopefully, once everybody gets healthy, we can see what that looks like, for sure.”
For now, that vision remains theoretical. But as Flagg continues to stack historic nights — even amid losses — the picture of what Dallas could look like at full strength grows clearer, and harder to ignore.
Veteran Perspective Inside an Unsettled Week
The trade deadline loomed over the locker room, but players insisted it hasn’t overtaken their focus.
“We honestly haven’t talked about it a ton,” Flagg said. “They’ve just prepared me for the reality that it’s a business. You never know what’s going to happen, so you just have to stay ready.”
Caleb Martin, who finished with 13 points, spoke at length about Flagg’s impact and the broader moment.
“He’s different for sure,” Martin said. “His game is so advanced and mature. He already understands where his spots are. You look up, and he’s got 35. Being that young, his game is very mature — and he’s still a kid. That’s wild to think about.”
Martin also addressed the difficulty of deadline week.
“It can be tough,” he said. “But all you can control is your mindset, your effort, and trying to block out the noise. Worrying about it doesn’t change anything.”
Kidd summed it up simply.
“That’s in the small print of the contract,” he said earlier. “That’s just being a pro.”
Up Next
The Mavericks remain home to face San Antonio on Thursday before visiting the San Antonio Spurs on Saturday, searching for health, consistency — and relief from a stretch that continues to test both.
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