It's never the defenseman's job to cover for the forwards', it really should be the other way around. Plenty of players make the common mistake of relying on their defenseman to correct mistakes and putting the full defensive workload on them. You see this far too often in the SHL, and due to the fact that a vast majority of players in the league tend to be offensively minded, it's troubling when forwards simply don't attempt to help out with the backcheck, or do the hard things in the corners. Every player, regardless of their real skill set, should be competently willing to sacrifice some of their offensive game on occasion if it means that the player can perform his or her job in the defensive end. Your defensemen will have more space to operate, get the puck out of the zone, and then they can worry about scoring.