He sure as hell wasn't fake, and I don't think Calzaghe ruined him, although he did give him a bad beating. Lacy, not unlike Vernon Forrest, never seemed to fully recovery from their torn-rotator cuff injuries. All bodies are different, though, and it can't be left unsaid that this is the most taxing of sports.
I think if anything would apply in this case, it was just that Lacy was a bit over-rated and never thoroughly tested until he faced Calzaghe. And we all know what happened in that 'fight'.