We absolutely could have traded him for value. We let him dangle in the wind for years exploring offers. We let him get injured and have a disasterous season. When he finally got healthy, we traded him at the nadir of his value and got less than nothing back in return. It was the equivalent of posting an ad on Craig's list for your sofa where anyone who is willing to pick it up can take it. His contract absolutely was a problem but it was made worse by combination of his injured / impaired play and the common knowledge that the team was desperate to get off his contract. Other overpaid players have been traded for much better value over the years.
With DJM, him being dangled out there with no push back absolutely cratered his value. He is a proven player on a value added contract (compare his numbers and his salary to FVV for example) and because teams knew we were desperate we couldn't get jack in return. Now Fields gets to run it back this summer trying to trade one his young point guards for value. If he is leaking stories about how Trae is one foot out the door he is choosing to tank the value for his own player before he even begins to market him. That is like putting your house on the market with a sign that says, "Desperate to sell. Ring bell to inquire within. Ask for dumba**."