His value can't go down; it can only go up. And if it goes up, that means he is worth keeping. If it doesn't go up, it is also worth keeping him for now, because if he stays at his current floor, he would be most valuable to match contracts for a midseason disgruntled star (ie KAT gets upset in Minnesota, etc). Trading him now means you are selling at his lowest point and trying to buy players from teams at the most optimistic time of the year.