I know what you're saying, but that's essentially what the left wing lock was.
The left Wing drops back and becomes a third d-man.
To play that formation all the time and with three dmen would probably be an ugly thing to see.
Sorry, but I think Kronwall, Smith, and White could be more effective in the "Lock" position than Brunner, Cleary, Abdelkader, and Tootoo.
This team needs to help out its goaltender and play a smarter game. There's no way it should be giving up this many outmanned attacks every game.
Play 3 forwards on the PP. That's fine. Play 3 defensemen 5 on 5. We got em on the roster. Might as well use em if our other guys are sucking it up.