You can still have bad hires. It happens rarely that the bar raising process outright fails, but it still happens, since the data you get out of an interview is

You can still have bad hires. It happens rarely that the bar raising process outright fails, but it still happens, since the data you get out of an interview is very limited. For example, we had a team member that not only was doing a bad job on his own stuff, he was a drain on morale and resources for the whole team, since he constantly complained about everything, he never tried to learn anything, he posted big commit dumps every few months - hundreds of commits at once - and the code quality on those was abysmal. Luckily we got rid of him pretty fast, but not fast enough.