Ummm...DWill was injured when they traded him. And Matthews leaving may have made DWill a little upset but it had little to do with him or Jerry leaving.
This might've been before you were on the board, but I actually talked in person to a long-time friend of Jerry's, Clifford Ray, at an LA Fitness in Orlando that summer. He told me Jerry was very upset that they lowballed Matthews and didn't sign him, having recently discussed this with him on the phone. If you don't know who Ray is, he was the Bulls center on the team that Jerry played with and later was the center on the Warriors' championship team led by Rick Barry, and often has been hired to work as a part-time coach for big men, most recently I believe for the Pistons.
There was a lot of talk in the news that DWill was upset about that, as well. Also, that summer they let Korver, who was another of DWill's buddies, walk. I don't know what Jerry's feelings were about that -- but I think Jerry liked Korver and if you remember, always played him in the 4th quarter, which won a number of games for the Jazz because of Korver's free throw ability.
I think this situation coincided with Greg Miller becoming owner (his refusal to pay for talent) and led to the tensions between Jerry and DWill. So, it was as if the first domino, not signing Matthews, led to the other events. Notice I say lowballed Matthews because Matthews had made it known that he wanted to stay with the Jazz but he was given a very low, preliminary offer. This gave the Blazers that opportunity to steal him from the Jazz.
As far as DWill's injuries -- it seems he had further injuries after he left the Jazz that led to his decline and other issues. I think if the status quo continued with the Jazz and Jerry at the helm, DWill's career would've turned out much differently.