Some people believe in the Peter Principle, that people are ultimately promoted until they reach a level of incompetence, and that it explains why so many upper level executives are such poor performers. While there is some truth to the theory, I also think high ranking executives are sometimes in their positions because they are one hit wonders.
Let's be honest. Business, like everything else in life, has components of luck and timing. Bill Gates would probably be successful no matter what had happened in his life, but put him in a different industry or shift his life by 5 years and he probably wouldn't be the richest man in the world. He wasn't just good, he also had good timing. You can use this luck and timing to your advantage by adopting the Mark Cuban theory of business which states that you if you just keep at it, keep trying things, and keep your eyes open, sooner or later you will be in the right place at the right time. But Mark Cuban wasn't talking about one hit wonders, he was talking about solid performers over the long-term who finally get the right opportunity.
One hit wonders are the opposite. Instead of being good over the long-term, they are consistently mediocre, maybe even lousy. But they did have the fortune to be in the right place at the right time, or to be associated with the right people, once in their lives. And that made them look good. This one event carries their career, and they rely on it for advancement. As they advance, and mistakenly believe they are skilled, they make horrible managers because they misunderstand the reasons for their success. They now have a false set of ideas about what it takes to be successful, which they force on employees, ruining some in the process. They never again have the success of that single powerful event, and they always blame it on everyone else.
So what do you do?
If you work for a one hit wonder, your best bet is to move to a different job or department. It is unlikely that you will much success working for someone that doesn't belong where they are.
If you manage people, you have to evaluate average performance, and figure out if a superstar performance is the expected return from excellent work, or a statistical outlier. I have been in meetings where an employee up for promotion was criticized, only to have someone bring up the "one hit." They will say something like "well, he did fix that problem with the ______ that no one could figure out." If you hear this, it doesn't mean promote him, it means dig deeper. If every other product of his work is questionable, you can't ignore that because of one good thing. Of course, on the flip side, the "one hit" could be a flash of genius that, given the right opportunities, may happen more often. You just have to gather more information to figure it out.
If you are a one hit wonder, you need to be honest with yourself. Don't take a promotion that you know you don't deserve, and don't try to leverage the success of your single event to break into other areas that you know nothing about. All you do is put yourself at risk of being exposed.
If you don't recognize the picture above, then you are probably too young to remember the song "Ice Ice Baby" by Vanilla Ice. He was the ultimate one hit wonder. He had the right song at the right time, and he mistakenly interpreted it as talent. Everything he has done since then has bombed. You can learn from his mistakes.
Celebrate success, when you have it, but don't lean too heavily on any one thing. Having one hit is not any reason to stop learning, trying, and growing – and anyway, you don't want to think that your best days are behind you. That is a lousy way to have to look at life.