My read on him, based on press coverage, is that he felt he had finally "made it" with the 4-year contract. He maybe relaxed a bit that summer, lost the battler's edge.
That was unfortunate, because he was going from a Cup-winning team in Chicago to a rebuilding team in Carolina. Not only did he lose his edge, but he went from a pretty ideal situation to one which was going to require some serious work (think Mrazek and McElhinney fighting for their careers this season).
I don't want to speculate and will couch this in euphemistic terms, but it seems pretty obvious that when he came out flat and the pressure started piling up on him, his off ice habits shifted from inadequate to counterproductive.
From what I can tell, he legitimately did prepare himself to compete this season. He lost 25 pounds in 4 months, which only happens with a pretty extreme amount of exercise and "diet" change. To some extent it was pure bad luck that he got hurt when he did, then McE came along and took his NHL job, and he never seemed quite right after that. Seems to me he might do well to take that buyout and get away from hockey for a while, start over with something else while he has a nest egg to take some risks.