Here's a tip...I don't believe Shattenkirk is any better defensively than ADA, but ADA is not nearly as good on the PP or even offensively in general.
The one difference that bother me, ADA at least looks somewhat engaged defensively even if he is making errors, Shattenkirk rarely looks like he is motivated defensively.
Smith similarly makes tons of errors but I get the sense he is trying to figure it out where as I get the idea Shattenkirk has already decided in his mind that he is not good defensively so he is only looking to create offense off the defensive play of someone else.
Shattenkirk is an elite offensive defenseman. One of the best in the NHL.
That covers a lot of what happens on the other end of the ice.