Con #1: Dillon Brooks is a distraction
Dillon Brooks' biggest knock is the fact that he's a distraction. People know him more for his trash-talking than his ability as a basketball player, and that's a problem.
Having Dillon Brooks in the Mavericks' locker room would not be the best idea because he brings negative baggage along with him.
He led the NBA this past season with 18 technical fouls, which resulted in two suspensions. Dallas already has a technical foul-prone player in Luka Doncic, and bringing another one in wouldn't be the best idea for Dallas.
Brooks also was a significant distraction for the team in the playoffs. As mentioned before, he made outlandish comments about LeBron James to reporters and then proceeded to lose three of their next four games. He followed up those comments by refusing to speak with the media three different times during the series.
The 6'7 wing did a whole lot of talking without backing it up. His trash-talking was so bad that the Memphis general manager Zach Kleiman said this.
" We're going to take a different approach as it pertains to [trash talk] next season...You'll see a different approach from this team, but at the same time, confidence is important."
This quote was indirect, but it seems to be directed at Brooks. Dallas doesn't need a player that is a distraction from the team's number one focus, winning.