Rick Nash was brought in after the 2012 season as a reaction to our inability to score in the playoffs during our ECF run. That specific purpose is the reason we traded multiple pieces for him. He has a large contract that was rewarded to him in Columbus with the expectation that he would be their star winger. Here, he is similarly expected to serve that role.
I don't think Nash is playing poorly right now, but neither is he living up to the expectations that his role on the team, contract, and history set. That's okay. We're winning. As long as we keep winning, that keeps the heat (relatively) off of Nash.
But if we start struggling and he still isn't putting the puck in the net, especially in the playoffs...