I watched him in the playoffs the other day. No better way to see how a guy really performs than the playoffs.
He is a decent shot blocker off the ball. His on ball defense is ok, he doesn't play the pick and roll amazingly well. Other than that he is kinda lost out there and not a super hustle player. He is a poor rebounder to for his size... due to his lack of effort.
End of the day, he doesn't have the mental and drive part of the game. Blazers don't want him.