The headline for NBA free agency has been, surprisingly, how the New York Knicks and the Dallas Mavericks are in a full-on war for Jalen Brunson. But apparently it's gone beyond just a professional battle – there's personal beef.

According to Knicks beat reporter Fred Katz of The Athletic, the Mavs are particularly peeved over a move that happened months ago. Knicks front office executives Leon Rose and World Wide Wes, alongside Julius Randle showed up at Game 1 of the Mavs-Jazz first round series in April.

Via Callin Shots podcast with Seth Partnow:

“I think that Dallas is very frustrated with the Knicks to be honest. I get the sense that they are really frustrated. I do not think that they liked those guys from the Knicks front office going to that Mavs-Jazz playoff game,” said Katz.

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Katz revealed that not only did that catch the ire of the Mavs braintrust. It also “ticked off” people from around the league for not displaying respectful etiquette in their very obvious pursuit of the star guard.

“I think that ticked off a lot of people around the league and not just people involved. I had execs from other teams, I had a lead executive like rant to me about how inappropriate that was,” Katz said.

“All I'm saying is that sometimes personal stuff gets in the way. I'm not saying this will for sure happen, but I think the Mavs are pretty annoyed with the Knicks. I think that's just not a factor to be ignored in this whole thing, too.”

Obviously, the Mavs want to keep Jalen Brunson for his basketball abilities. But the human element in trying to stifle the Knicks' attempt after their disrespectful stunt likely plays a bit of a role there, too.