Remember when Cliff Lee was a bad pitcher? His baseball card won't do his badness justice, thanks to those 14- and 18-win seasons he picked up while allowing a ton of home runs and just before totally falling apart in 2007, but he was the kind of functional talented-headcase type where people tut tut at the inevitable 6.29 ERA season and say—it was bound to happen anyway.
Or if they don't do that they're at least less likely than usual to predict the ensuing 22-3, 2.54 ERA, 5 K:BB Cy Young season. In the four years since Lee's played for four teams, pitched 900 innings gotten his strikeout rate even higher and kept his walk rate just as low—his K:BB ratio over that period is 5.65, which would lead baseball most years.
Roy Halladay had an even worse burnout, but he hadn't had such a long period of relative ordinariness before it—that's what makes Cliff Lee confusing. It's like if we'd seen Dazzy Vance struggle for all that time in the Major Leagues, and then instead of overpowering hitters he'd become the ultimate finesse artist, the quintessential "smart" pitcher.
Chris Carpenter's similar, but we have some pegs on which to hang the narrative—he got hurt and he changed teams, moving to a Dave Duncan squad—the ultimate excuse for a veteran rehabilitation. He was also kind enough to pitch one season at a great-but-not-spectacular level before competing for three Cy Young awards, and now that he's managed to recover twice from career-ending arm problems he has new, even more confounding narratives to compete with that first one.