Politics is a lot like acting or sports. It’s hard to give up the limelight, and the key is to do it at or approaching the peak of your career, and not before you start heading downhill.Cook is confusing the politician, ballplayer, and actor with their audience. For the audience, it's a good thing to remember people at their peak. We want to remember Brando in Waterfront, not in Superman; we want to remember Mays with the Giants, not with the Mets; we want to remember DiMaggio with the Yankees, not with Mr. Coffee.
But for the ballplayer, actor, and politician...it's their life, not ours. Here's the thing: when you walk away, it's gone. That's especially true, and easiest to see, for athletes. Think about it for an aging baseball player, for a Ken Griffey or John Smoltz. They've been playing baseball their entire remembered lives. They probably really like playing baseball; surely, they'll never find anything else they were as good at. And once they retire from major league baseball, that's it. They will never play baseball again. Oh, they might show up at spring training as special coaches and fool around on the field a little bit, but otherwise it's totally gone. That's especially true for football players (a friendly game of touch is pretty far from real football), but mostly true for almost all of the professional team sports.
The point here is that from the point of view of the athlete, that memory of greatness is, most likely, not very important. Now, I'm sure there are some who don't like the game very much, and want to get out once they've made some money at it. In the rougher sports, there's the incentive to get out to avoid risking one's future health and comfort. And some might feel embarrassed to be no longer as good as they once were. But they don't watch themselves; they aren't the fans. What Charlie Cook is talking about isn't, in almost all cases, part of the lived experience of the athlete (actor, or pol) him or herself. Nor should it be; it's our experience, as the audience.
The idea here is that it isn't the responsibility of the athlete, the actor, or the pol to bow out gracefully because they've passed their peak. Now, I do think that politicians do have a responsibility to get out if they can't really do the job at all (ahem, Senator Byrd?). And I like Andrew Gelman's idea that parties should be aggressively counter-cyclical -- for example, the Republicans could have urged Chuck Grassley and John McCain and other aging Senators to retire this year, since it's apt to be a good one for the GOP to keep their seats. Frankly, I also wish that voters were more apt to punish aging pols. But beyond that, their lives are their own, and they don't owe it to anyone to quit if they can still do their jobs. They certainly don't owe it to Congress-watchers who want to remember them at their best.