I wouldn't call Ghost terrible in the D-zone, but average at best is fair, he's good with the stick, but physically the weakest of our D-men and he makes some mind fart passes. He's certainly no Provorov!
Manning is a solid 3rd pair D-man, I think watching Provorov and Gudas our standards have risen back to the days of Kimmo and Coburn in their prime, the last couple years any decent D play was a cause for celebration.
MDZ is frustrating right now, but I'll give him another month to get back to where he should be, but unless he has a great finish, I don't see him back next year, when Sanheim and Morin come up, you have to play them, Hagg and Wilcox have a shot, so MDZ is your 6th D-man with guys pushing him. And Manning is more physical and gives you an edge for road games.
MacDonald is passable, if he was on a 3rd pair with the two top pairs playing 20+ minutes, no one would complain if he was being paid like Schultz. Because he'd be the equivalent of Schultz (moree offense, less defense), minute eating depth. But I'd keep Manning over him, Manning makes more mistakes, but provides the same offense and a lot more toughness.