Gonzales, alas, is far from being the only person in the administration who excelled in previous jobs only to reach his level of incompetence. I am on record praising Dick Cheney's selection as George Bush's running mate in 2000. As President Gerald Ford's chief of staff and as secretary of defense under the first President Bush, he had demonstrated sound judgment and a cool head in challenging situations.
He had the good sense, for example, to reject the idea of marching to Baghdad to topple Saddam Hussein during the first Iraq war. "Once we had rounded him up and gotten rid of his government," Cheney said later, "then the question is what do you put in its place?" Only when he was elevated to the vice presidency did he start following orders transmitted through his dental fillings from the Death Star.
Harriet Miers had an excellent career as a lawyer, representing Microsoft and Disney and serving as president of the Texas bar association on her way to becoming White House counsel. She was so good at this last job that her boss decided she would make a swell addition to the Supreme Court. Her reward for capable and loyal service was to be exposed as pitifully unfit for a higher job, and to become a national synonym for mediocrity.
Unfortunately, there is no way for presidents or anyone to know when a talented performer will finally come up short. So, as Peter pointed out, it is up to each of us to avert being promoted too far through the use "creative incompetence" -- such as parking in the boss's space, wearing too much perfume, hinting at a sordid private life or otherwise creating the impression that you've already reached the outer limits of your capacities.
Gonzales may wish today that back in Texas, he had occasionally showed up for work with stubble on his chin or lipstick on his collar. It would have saved him and the rest of us a lot of trouble.