However, a source close to the situation disputed who initiated that
argument, and said that it wasn't the first altercation Del Negro has
had with management. The source said that Del Negro and Bulls general
manager Gar Forman had an altercation in Forman's office that was
similar, but did not give details.
"So this was not the first time [Del Negro] exhibited this behavior," the source said.
Well now it appears to be a "he said" "she said" situation.
It seems likely that Del Negro's camp leaked the original story to Adrian Wojnarowski while the Bulls leaked this version to Melissa Isaacson.
So the real question is which side is telling the truth? It's a typical PR move to leak this kind of information (which even includes some bonus character assassination of a previous incident) in order to muddle the issue.
Of course, it also makes sense to do leak this side of the story if it's true.
Anyway, at this point, it's likely we'll ever really know what happened.