PK and Risto are NOT noted puck movers and I'd argue both are considered overrated or expendable players to their recent and current clubs respectively.
There are a lot of players who do both but the point I think McDNicks is making is that if you take away the puck movement, it'd be a lot more damaging to them as defenseman than their physicality. I actually don't think Larsson is the worst puck carrier in the world, and at his best he has the ability to skate pucks out of danger areas without panicking. Part of the reason it's been so noticable is the rest of the group wasn't doing it very well either.
With Bear and Persson, and Tippett coaching a more varied and less spread out breakout, it's been far less of an issue for Russell, Nurse and Benning and it will probably be less of an issue for Larsson once he gets a chance to play. I do think cyclebreakers and toughness CAN matter, but on the list of important things to have as a defenseman, it's a lot lower than puck movement. Ideally all six would be able to pass the puck up the ice and some of those guys would also be tough in the corners and along the boards.
Also, the Boston Bruins aren't that tough. I really wish people would stop spreading that myth about them and the Blues.