Celtics Rookie Slammed by NBA Insider for Disappointing Summer League Performance, Raises Concerns About Readiness for Boston’s Regular Season Roster Spot

The Boston Celtics entered the 2025 NBA Summer League in Las Vegas with a wave of anticipation surrounding their newest rookie. After an aggressive draft night move and glowing pre-draft evaluations, fans and analysts alike were eager to see if the franchise’s first-year prospect could show flashes of stardom — or at least immediate role-player potential.

Unfortunately, not everything has gone according to plan.

In a sharply worded segment aired on NBA Today, veteran NBA insider Tim MacMahon didn’t hold back when evaluating the Celtics rookie’s underwhelming showing in Vegas. While the Celtics organization remains publicly supportive of the young player, the early signs from Summer League have prompted growing concern — and in MacMahon’s view, “clear red flags” — regarding the rookie’s preparedness to contribute in meaningful ways this season.

High Expectations and a Rocky Start

The Celtics selected [Player Name] — a 6-foot-7 wing with defensive upside and a fluid shooting stroke — in the mid-first round of the 2025 NBA Draft, hoping to add depth to their perimeter rotation. Coming off a strong final year at [College/Overseas Club], many expected a smooth transition to the pros.

However, the rookie’s Summer League stats paint a different picture. Through five games, [Player Name] has averaged just 7.2 points per game on 34% shooting from the field, including a dismal 21% from beyond the arc. Even more troubling, he’s committed more turnovers (3.1 per game) than assists (2.4 per game), often struggling with decision-making under defensive pressure.

MacMahon didn’t mince words in his breakdown:

“This isn’t about box scores — it’s about body language, feel, pace. And right now, [Player Name] looks like a guy drowning out there. He doesn’t look ready. You expect growing pains, but not to this degree.”

Criticism Mounts From Multiple Angles

While some have defended the rookie’s slow start as part of the typical adjustment curve, others across the NBA media landscape echoed MacMahon’s sentiments.

ESPN’s Kevin Pelton wrote in his Summer League Stock Watch column,

“Few prospects have seen their stock slide more than [Player Name]. He’s tentative when initiating the offense and hasn’t established any identity on the floor.”

Meanwhile, former NBA player Kendrick Perkins voiced his frustration on NBA Countdown:

“The Celtics are trying to win championships. They don’t have time for projects that don’t develop. If this is your first impression? That’s not going to cut it in Boston.”

Brad Stevens Preaches Patience

Despite the media backlash, Celtics President of Basketball Operations Brad Stevens is preaching patience.

Speaking to The Boston Globe following a recent Summer League loss, Stevens downplayed the rookie’s struggles, saying:

“It’s a learning environment. We’ve seen plenty of guys look lost in Summer League and then shine in October. [Player Name] is working hard, and we believe in his long-term potential.”

Stevens cited examples of stars like Jaylen Brown and Jayson Tatum, both of whom had bumpy stretches in Summer League before evolving into All-NBA talents.

Still, Stevens is also aware of the team’s win-now mentality, especially after coming off a 2024-25 season where the Celtics reached the Eastern Conference Finals. With a veteran-heavy roster and championship aspirations, Boston needs every bench player to be ready and reliable.

What’s Gone Wrong?

Several scouts suggest that the rookie’s performance issues stem from his lack of explosiveness and poor decision-making when facing aggressive defensive coverages.

One Western Conference scout observed:

“He’s struggling to create separation. The handle isn’t tight enough, and he’s hesitant — which leads to turnovers. On defense, he gets caught watching the ball and loses his man too often.”

Others point to confidence. After a few rough outings, the rookie appears hesitant and unsure of his role on the floor. That lack of conviction is becoming evident to fans as well.

Social Media Backlash

Celtics fans, notorious for their passionate and sometimes unforgiving reactions, haven’t spared the rookie either. Hashtags like #SummerLeagueBust and #NotReadyForBoston trended briefly on Celtics Twitter after a 3-point, 6-turnover game against the Kings.

One fan tweeted:

“We needed a shooter off the bench. What we got looks like another G-League project. Not what we were promised.”

Another added:

“He better hope Brad and Joe believe in him, because the rest of us aren’t seeing it right now.”

However, some fans are calling for calm and maturity, noting that stars like Derrick White and Khris Middleton took time to find their footing in the league.

Coach Joe Mazzulla’s Role in Development

Celtics head coach Joe Mazzulla will play a pivotal role in determining how quickly the rookie develops — and whether he earns playing time this season.

Mazzulla told reporters after the Summer League finale:

“There’s a foundation there — the kid works. But it’s going to take time. Our system isn’t easy, and the NBA isn’t either. We’ll coach him hard, but we’ll support him too.”

The Celtics coaching staff is reportedly working closely with the rookie on simplifying reads, speeding up his decision-making, and improving conditioning.

What’s Next?

The Celtics must now decide whether the rookie is best suited for a role on the NBA roster or if a two-way contract or G-League assignment would benefit his development. With the roster already deep and competitive, especially in the wing positions, cracking the rotation will be a steep uphill battle.

Boston has a history of strong G-League player development — just look at JD Davison’s progression before his recent signing with Houston — so this may be a wise route.

It’s far too early to declare any rookie a bust after five Summer League games. However, expectations were high — perhaps too high — for this particular Celtics pick. The negative attention he’s received isn’t without cause, but it also doesn’t tell the full story of a young player navigating the biggest transition of his basketball life.

For now, he remains a work-in-progress.

As Tim MacMahon concluded in his analysis:

“You hope this motivates him. Because Boston’s not a place where you get three or four years to figure it out. You either produce — or you pack your bags.”

Whether the Celtics rookie can tune out the noise, absorb the lessons, and emerge stronger in training camp remains to be seen. But one thing is certain: the pressure of wearing green and white is real — and this summer, it’s already begun.