For some reason I'm fairly confident Martin will return to the level he played at his first season as a Penguin. I think a lot of fans are unfairly holding him to another standard that most other players seem to be getting a pass on after last season. Martin playing at a level he did when he first signed is a very good deal for his cap hit. He is a great skater, smart, and has a very active stick. He didn't show much of that last season but these are not things that completely disappear overnight. He looked lost and confused as did most Penguins defenseman last season.
The change that needs to happen most on defense is from the coaching staff. The Penguins need to simplify their game in their own end. We won with a defense very similar to what the Rangers have been doing of late. A style to lends itself to collapsing around the net and committing on defense. The problem with what they they ran last season is that every scheme seemed to be built around quickly exiting the zone, which is great when it works, but never addressing what happens if things don't immediately transition the way they want. As soon as something didn't go exactly the way the Pens wanted in their own end it was meltdown city. And players that are very impressive when what they are taught to do happens, suddenly look like they have no idea what they are doing on the ice.
A player like Martin came from a very structured environment into one that seems to say "Hey, this is what we want to have happen. If anything else besides that happens, you're on your own.". If the Pens realize what a glaring coaching staff gaffe it was in our own end last year and simplify things, Martin will be a much more valuable player. One that, looking at our depth chart and the ages next to them on defense, we really can't afford to lose as things stand, imo.