I've seen all but a couple of the games he's played in, with a another few coming up. Hard to compare because of the way AHL hockey is played, generally less structured, regardless of the systems ostensibly being played, but I've thought for a while that the presumed awfulness of his D game is vastly overstated, and nothing I've seen this year (or in TC/preseason) changes that. He's not a box-out type of player but he uses his body and stick well to make quick plays off the boards and intercept puck and player traffic, anticipates play effectively and his top-end mobility and IQ help make him an excellent transition player, either through passing or on the rush. Nothing I've ever seen from him, including his WJC play, has suggested that he's got some fatal flaw that means he won't be up to the job of defending at a high level.
There's no doubt he has given up on a few plays in games I've watched and struggled a bit on the boards -- much more than usual, I'd say -- and I suspect this is down to nagging injury rather than capacity. Several times he's been seen slapping his stick and cursing himself for missing on a check or making a poor play. He's always been more of a Heinola/Pionk/early JMo player, but he has excellent vision and passing and the ability to separate players from pucks and reverse the run of play quickly when he's on. I honestly think he has been more or less injured all year, and I wonder if they just let him recover fully and then look to give him a shot in the NY.
I don't know whether he's a "PoMO-type" defenceman or not, or what that even means really, since Toby and Pionk and JMo were all absolutely PoMo Dmen, just as Buff was, and then Trouba, Stu, Chairot, etc. He's definitely an upgrade on two of our pairings, IMO, but groin injuries can mess with all aspects of your game, especially as D or goalie, and can lead to hip problems also. Still hopeful, and they'd be nuts to give up on him I think. Super-talented D, even those with some warts, aren't easy to come by -- just look at how many objectively worse players have had long careers in the NHL (Ceci, Johnson, etc. etc). I do think some here who are quick to write him off or appeal to the Jets system authority -- Look at Petan and Burmi and whomever!!! -- need to watch him play. He's far and away the best D on the team even when he's having a bad game, and often the best D on the ice, period.