May 13, 2025; Chicago, Il, USA; Cooper Flagg (51) participates in the 2025 NBA Draft Combine at Wintrust Arena. Mandatory Credit: David Banks-Imagn Images

'He Beat Himself Up' – Dallas Mavericks’ Rookie Wasn’t Happy With His Summer League Debut

Originally posted on Hardwood Heroics | By Reign Amurao | Last updated Jul 14, 2025 7:54 AM ET

The Dallas Mavericks have announced on Saturday that they’ve shut down Cooper Flagg for the rest of the NBA Summer League. The decision came after Flagg’s 31-point performance against the San Antonio Spurs earlier that day. After the Duke star had his best game, by far, the Mavericks thought it would be better to let him sit for the rest of the tournament.

Flagg didn’t have the best start to his Summer League stint. The Mavericks faced the Los Angeles Lakers and the rookie forward had an underwhelming game. He finished with 10 points on 5-for-21 shooting from the field, including a 0-for-5 shooting from oustide the arc.

Although Dallas secured the 87-85 win, Flagg wasn’t happy with the way he played. His trainer, Matt MacKenzie, spoke to Sportskeeda’s Mark Medina and revealed the rookie’s assessment on his play.

“He beat himself up after the night against LA,” MacKenzie said. “He obviously wasn’t happy with the way he shot the ball. He felt like he got sped up. He felt like he rushed a lot of his shots. So we had a conversation [on Friday] just about how we needed him to settle in and we needed him to understand that he has the ability to impact the game in so many different ways. When he doesn’t have his shot falling, he has to make sure that he’s pursuing rebounds and make sure that he’s doing all the little things out there to get himself going. And then the shots will fall.”

Fortunately, Flagg was able to get into his rhythm and it helped him perfom better. He only played two games this summer and will continue the offseason on the sidelines.

The Dallas Mavericks wants to make sure that the rookie forward doesn’t get hurt during the tournament and is ready before the start of the 2025-26 NBA season.

Flagg would’ve wanted to play in the Summer League for the Dallas Mavericks

May 13, 2025; Chicago, Il, USA; Cooper Flagg (51) and Khaman Maluach(14) participate in the 2025 NBA Draft Combine at Wintrust Arena. Mandatory Credit: David Banks-Imagn Images

When Flagg was shut down, it wasn’t his decision to sit out for the rest of the tournament. His trainer revealed that he didn’t want to get shut down and wanted to continue with the Summer League. However, the Dallas Mavericks think it’s better for him to remain in the sidelines.

“I think for (Cooper Flagg), he wants to continue to learn and continue to get better and he doesn’t necessarily want to be shut down,” MacKenzie said.

Even his trainer wants Flagg to continue playing in the Summer League.