Being good defensively means two different things today. There is being good defensively, where you are in your own zone and you don’t have the puck, which Shattenkirk isn’t very good at. And then there is the other being good defensively, which includes the benefit of the total amount drone time and shots you prevent by virtue of creating offense outside of your own zone. This is what makes Shattenkirk such an effective defender, he suppresses shots by creating offense.
Now... why Shattenkirk is getting PK time when we are basically tied up in our zone, is a Cooperism which I cannot explain.