I've only really watched your team since the deadline when my favorite Front was sent there, so I might be a bit biased.
I think that your lock down d man is Steen if he is able to play, the other 2 you mentioned seem to be out of position many times. I've never seen a Dman lay down on the ice and lose his stick as much as 24. I think an overall team committment to Dzone is the only way.
This also holds true with your goalies. Limiting shots on these guys is the key, If it were me I'd have your wingers up a step or two higher on their Dmen. They are very active on the blueline and the less room you give them, the better. I'm not too confident in the goalies, they are both big, so I hope everything hits them.
My hope is that Stewart, with the way he has been playing will be allowed to step up and be that playoff surprise. He is physical, not intimidated and can make room for himself and his linemates. He does have to continue to be disciplined as he has been lately.
Good luck to you guys.