I think this list is very statistics based. Hunter had almost twice as many steals as Gabe.There is no way Tyrese Hunter was a better defender than Gabe was.
And #3 on this list, Ryan Kalkbrenner, is a very good shot blocker at over 2.5 per game, but I wouldn't say he's an elite low post defender.
Maybe likewise Osun avgd almost 3 blocks per game, which is maybe why he's so high, but having watched him play some, he does look pretty good one on one in the post.