Perhaps because it was a meaningless sample size of garbage time minutes on a crappy team.
He averaged 8.8 minutes of garbage time a game. Memphis went 7-27 in games he played in and only won a single game he played more than 8 minutes. He averaged 5 MPG in the 7 games Memphis won and almost twice that much in the 27 games they lost. Even a crap team like Memphis wasn't going to risk playing Darius significant minutes in any game they actually had a chance to win.
Chris Wallace's motive was clear and transparent - to screw the Blazers out of cap space. Miles was never a part of their future plans. If they were looking for a player to keep beyond the end of last season, they would have been better off giving the roster spot and minutes to a D-League call-up. But, that would not have achieved his goal of screwing another team, one of the few others that would have cap space last summer.
BNM