Because he's good at following orders: "tank the season, do not make the playoffs"
it's the only thing that makes sense:
not trading anybody
buying out two good players that could have been traded at least for something
not making any plays different that "melo, you shoot it"
not displaying any defensive system whatsoever
overplaying melo probably to get him tired or injured and to stop scoring
let's face it, we are not making the playoffs on prupose