Why? He showed nothing with Boston, his hops are pretty much gone, and he doesn't have the fundamentals to compensate for his lost athleticism.
Plus, Miles seemingly gave this comback effort everything he had, to the length of cheating with dietary supplements. Now that it is obvious that he is at best a practice-squad player, the real question is how will Darius react to this failure. I had to laugh when I saw him sitting next to KG on the bench, yucking it up like an All-Star, because his current game should have had him elbowing it out with Scalabrine for the stool at the end of the bench.