Too many people think that the decisions you make are judged by the quality of the outcome which just wrong headed. You can make the 100% right decision, and it turns out with a less than desirable outcome. Yet, that decision is still the optimal one to make. There is virtually no scenario where the Spurs would have gotten more for DJM or where they could have reasonably expected him to make this team good enough to warrant keeping him and paying him. When you realize that, then the trade to Atlanta is obviously the right move to make every single time. There are scenarios when things don't play out as well as others, but there's really no reason for the Spurs to think twice about that trade.
Few people on this site were as high on that kid as I was/am. I still don't see how any trade would have been better (shocked they got as much as they did, quite frankly). I don't see how anything can be up in the air when the Spurs sold DJM at what is possibly the highest price they could have reasonably gotten for him.