Interesting question. I think the "good years" were such a long stretch from Bob to Tom that it was easy to think it would continue forever. Just a guess but no one probably gave it a thought as it became such common place to play for titles that everyone assumed it would continue forever. Human nature always fails to recognize the giftedness of certain people wishing to think it all "just happens" because of a system, state or upper leadership when in fact there are always a handful of highly motivated and extremely bright pioneers that rise above everyone and we had that.
Then the common thought is just insert so and so and try and run the same system and it will be fine, then well so and so is gone, so the system must be broken, now lets try.......
It happens in business, politics and all facets of life. Although most would say they didn't expect it, if they have some years under their belt, they should not be surprised it happened.