Summary
Brunson has shown to be a solid backup point guard. He 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. He can initiate or absorb contact on drives to finish at the rim, as he has finished above-average for his position or better on field goal percent at the rim each of his first three seasons, per Cleaning the Glass. He's been just as good in the midrange. Brunson shot 40% from three this season, and if he keeps that up he will be a real high-efficiency scorer.

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.
 
Cap Considerations
Brunson's $1.8 million salary for 2021-2022 is non-guaranteed, and if he is waived he will become an unrestricted free agent and the Mavericks will have no form of Bird rights on him. It's very unlikely the Mavs waive Brunson, and if he did he would likely be claimed before hitting free agency. If he is waived, teams could claim him off waivers, but would need to fit his salary within cap space or an exception to do so, as his contract doesn't fit within the minimum salary exception as it was a four-year contract.

If Brunson becomes a free agent, other teams will have multiple ways to sign him as even teams without cap space could possibly use either of the Non-Taxpayer MLE, Taxpayer MLE, or possibly even the Room MLE to sign him. I would also say that in the unlikely scenario Brunson is waived and clears waivers, his value will have dropped low enough that he would only have offers for the minimum.