It's a very good golf course, plays exactly like good players think a course ought to play, is in excellent condition, has some tournament history, and has been tweaked based on tournament history, a la Pinehurst, Augusta, etc. to be even better.
Like any ranking, you could drop it ten or twenty spots personally, and members would be insulted, but it would still be a very good golf course. It is in the right neighborhood, even if you think it could be located "a few streets over." Like Andy, I think the consistency of the rankings speak to its overall quality.
Also, its one of the few top courses I have played on separate occaisions separated by many years and I wasn't dissapointed the second time around, as I think we all are on some "pretenders" which I took as a good sign that it was as good as I thought.