Quality is more important than quantity in engineering, so a mediocre hire can be a net negative. In so many ways:

- consuming time and attention from people who help them

- time spend checking and fixing their work

- additional maintenance costs from poorly thought out solutions

- time spent reproducing and fixing bugs

- lowering morale of better engineers

- creating whatever the opposite of “a culture of excellence” is

- consuming management time in performance management

- inability to interview or saying “yes” to even worse hires