Looking at how the Penguins defenseman compare to one another in terms of on-ice goal differential, Christian Ehrhoff is in his own category, really.
Not only has he been on-ice for 28 5v5 Penguins goals, but his number of goals against rivals that of other Penguins defensemen with significantly less ice time (Simon Despres and Rob Scuderi).
It's not unreasonable to expect these numbers to get even better, as he seems to have become more accustomed to the Penguins system. That's kind of scary, in a way, because even during the beginning of the season, he was very quietly solid and kind of amazing.
It's also a very good thing that the only defenseman with a negative differential is Brian Dumoulin, and being that he has only played 3 games, you can expect those numbers to increase with more ice time as well.
I'm not smart enough to get into systems analysis, but you have to wonder how much of this is a product of Mike Johnston and his allowance of letting defensemen make reads themselves and slow the play down in their own end instead of simply needing to push the puck forward as fast as possible.
Either way, it's been a ton of fun to watch and very enjoyable.
(Data for graph via War on Ice)