Mavericks rookie Cooper Flagg has already turned heads in his first two NBA 2K26 Summer League games. The main takeaways from his early showings offer a glimpse into his potential and could help shape expectations for his fantasy basketball value in the 2025-26 season.

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Flagg was much better in his second performance (vs. Spurs) than his first (vs. Lakers). Against the Lakers, he took too many tough, contested mid-range jumpers. He drove harder to the basket in the second game, fueling a better and more efficient outcome. The constant in both games was that he looked the most comfortable in transition, often starting or ending a fast break. His combination of size and athleticism is tough for opposing players to deal with when Flagg gets a head of steam.

Although teammate Ryan Nembhard handled traditional point guard duties, Flagg was asked to create plenty in the halfcourt. More often that resulted in shots for himself or dish-out passes rather than assists. It’s possible, if not likely, he averages more assists during the season. He was a great passer in Duke’s system. Summer League can be hit or miss when it comes to structure. There should be more opportunities for him to show off his passing IQ and vision when working through Dallas’ playbook and sets. The fact he committed only 1.5 turnovers in the Summer League environment with his usage is impressive. However, against stronger, quicker and headier NBA defenders — there may be some growing pains as a ball handler.

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Flagg was a 39% 3-point shooter in college but struggled in Summer League. That said, he wasn’t shy, essentially doubling his volume from Duke. Flagg will need to space for the Mavericks but probably won’t be asked to shoot seven 3s per game. The ones he does shoot will more likely be open, catch-and-shoot 3-pointers rather than pull-ups. There are scouts who aren’t in love with his shot mechanics, so there could still be some hot-and-cold stretches during the year.

Defensively, Flagg’s instincts and athleticism were on display. He didn’t rack up gaudy steals and blocks numbers but was usually in position to help and didn’t shy away from sticking his hand in to poke the ball away from a driver. He also contested shots without fouling. At the NBA level, it may be tough for him to rack up big block numbers while presumably sharing the court with Anthony Davis and one of Dereck Lively II or Daniel Gafford. The rebounding numbers also weren’t gaudy, and I won’t expect them to be in the aforementioned environment. Flagg may be asked more to leak out in transition than to crash the glass.

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2025-26 fantasy outlook

What is Flagg’s fantasy basketball potential as a rookie? I don’t think his two Summer League performances changed anyone’s mind. People who love his instincts and athleticism saw that. People who thought he’d have growing pains in the halfcourt saw that. In the context of the Mavs, Flagg has the upside to be a co-second option with D’Angelo Russell (filling in for Kyrie Irving), behind Anthony Davis — whether he immediately actualizes that is unclear. But it won’t be easy for Flagg to rack up rebounds or blocks with Dallas’ big lineup, and he’ll need to establish himself as a perimeter shooting threat — both on and off the ball — to maximize his effectiveness.