I think "Peja's not in shape, therefore he is injured" is a bit simplistic.
Webb always worked out hard every summer, but his body just broke down. Bobby was ferocious and full of energy, and his body just broke down. Meanwhile Vlade never touched a weight and ran through almost his entire career with nary an injury. And Peja..well, he's hardly ferocious, but his body just may be breaking down. He's never come in camp looking flabby, never had obvious conditioning problems other than the career-long stamina issues during games. And really, in his most injury wracked campaign before this one -- 02-03 -- the complaint was the opposite. The idiot ran off to play for his NT on a bum ankle and ended up struggling with ankle/foot issues well into the following season. Last tiem we were worried about his future health actually.
Where his lack of offseason work has always hurt is in his fundamental lack of improvement, and indeed regression over the years. I think those who claim he does not truly love the game may be largely correct, and certianly its long since become very obvious there isn't even a hint of fire in his belly. Of the competitve drive to be absolutely the best he could be.
But the injuries? Peja has always gotten nicked up and missed time. Never been remotely an ironman. And of course I think that he combines a very low pain threshhold for a professional athlete with the aforementioned lack of fire to really adopt a lassiez faire "why should I play through pain" attitude when he's hurting. So he misses time others woudl not necessarily miss.
Not much of the above is complimentary, but the one thing I DON'T think we have any real evidence of is Peja not staying in shape. In fact if there is one line I would generally draw with Peja critricisms it is that I think he is a professional. That he will come to camp in shape in professional manner. Prepare professionally. Do all the minimum level things you expect out of a pro. He just will not go above and beyond, because again, he's a professional, and this is a job for him, not a passion.