Summary
Brunson has shown to be one of the best backup point guards in the league, and the Mavericks moved him into a starting role in '21-'22 after Tim Hardaway Jr. got injured. The question now is how good of a starting point guard can he be, and is there a team that's filling to pay him starting-level money to be their point guard of the future?

Brunson can spot-up, make plays off-the-dribble, and overall just has a real knack for making plays. He can score at all levels, and knows how to use his body to create space in tight spaces using great footwork to pivot around defenders. He can initiate or absorb contact on drives to finish at the rim, as his 68% field goal percentage at the rim in '21-'22 was near the top of the league for a guard, per Cleaning the Glass.

He's also a very good midrange shooter, as he can snake pick-and-rolls to get to his spots, and has nice touch in that area. Brunson shot 40% from three in '20-'21, and while that was down to 37% this season, that is still above average and his overall efficiency has been very solid due to his good two-point shooting.

On defense, what he lacks in height he makes up for in strength. While not having a lot of length can make it harder for him to contest, he's stout enough to at least not be bullied by bigger guards and wings.

Brunson did not have a great playoff series in 2021 against the Clippers, only playing 15.6 minutes per game and overall not being very effective. However, he showed in the 2022 playoffs that he could be effective when the games matter most, having some big scoring games for the Mavericks. He may not be a true #2 scoring option on a title contender, but he's an above-average starting guard and will likely get paid like one.
 
Cap Considerations
Brunson will be an unrestricted free agent with a $1.8 million cap hold and full Bird Rights. Since the Mavs will likely be operating over the salary cap, they will retain Brunson's Bird rights, and have no restrictions on re-signing him.

If a player has a smaller cap hold than his starting salary, his team can use cap space to sign-free agents before using Bird Rights to re-sign its own free agents. Since the Mavs will likely not have cap room, Brunson's cap hold will not play a factor.
 
Since Brunson will demand a starting salary of more than the full $10.3 million Non-Taxpayer Mid-Level Exception, only teams with cap space will be able to sign him. If Brunson and an over-the-cap team have mutual interest, sign-and-trade options can be explored.