Markov started out putting up a lot of points and letting mediocre players deke and score on a pairing with Brisebois. He focused more on D as time went on, and got a lot of coaching. I remember stories that he was reluctant to change in ways the coaching staff wanted until he started seeing the benefits. He worked out his game.
Hutson's defensive issues are more physical. Markov wasn't huge but players overall weren't as big, either, so he wasn't at a huge disadvantage. We'll see how coachable Hutson is, how good the current habs coaches are, and whether he can deal with the size difference. He looked great on offense with the habs, but they were often hemmed in their zone when he was on, and he ended up -2 in spite of putting up points. He has a lot of time to work out his defensive game, but he's got a long way to go to be a playoff asset.
I was surprised at how good Mailloux looks. I haven't seen enough of Reinbacher to say anything about him. As a higher pick and a bigger, more responsible player, I expect he has a higher floor than the other two.