Kadeem Allen is one of my favorite defenders. I think he's very underrated, but as saltlover said, I cannot imagine demand is that high for him. Considering he's not that great at offense, cannot handle the ball that well, and he's a tweener, because he's too undersized to play the 2 well, and he's not justifiable to play make well enough at the 1.
He's definitely one of my favorite defenders to watch, so who knows?