The Pens adressed their defense... and lost one of the best defenseman in the league. They lost more than they gained. I'm more concerned with the Devils.
As for McPhee, you guys need to calm down. It's not his fault his team can't win in the playoffs. There were so many times where they had 50 shots on goal, and countless great opportunities. Halak played out of his mind, nothing you can do about that. That's the coaches job. As a whole, the defense played pretty well, the Habs didn't score much throughout the series, but that said, Mike Green must have given them at least 6 goals directly by himself, and that can't be tolerated. But agani, that's on the coach.
All McPhee has done is build a team perenially atop the standings. I am not a believer in a team that has "winners," that's bull, there's no trade that can fix that, no signing either. The defense could use improvement, but that's the system... it's not built to stop goals. And to win in the playoffs, you may have to change those ways. Again, on the coach. And just by virtue of adding Alzner and Carlson, the defense has improved, in fact.