In round 1 they faced a banged up Ottawa team that only figured out a somewhat effective game plan vs. the Pens at the game 5 mark of the series. Another key to a Pens victory in that series was Ottawa's goal-tending was even worse than Pittsburgh.
Even still people were saying MAF is money, he doesn't need a 900 or higher save percentage. He'll step up when he's needed. Don't worry about the Pens they're doing what they need to do to win like real champions. Just look at Crosby he's unstoppable. What we saw in that Montreal series was, with a proper game plan, the Pens and even Crosby were quite stoppable. Sure Halak was phenomenal at times but he didn't single handedly win this series. Absolutely it could be argued he did so vs. the Caps of course.
Have a read of this. It's a pretty good take on what happened to the Pens.