The purpose of anybody on your team is to raise the productivity of your team as a whole. That's really the beginning and end of it: does your team do more with

The purpose of anybody on your team is to raise the productivity of your team as a whole. That's really the beginning and end of it: does your team do more with this hire than without it? Individual contributions are part of answering that question, but they're not the whole picture. In one limit case, some recluse locks themself in a broom closet and programs a well-defined isolated chunk of code by themselves, and delivers it as a library. In this case there's nothing except their individual contribution. In the other case, you have managers which don't touch the code at all but greatly affect everyone else's productivity (for better or worse--and it is possible to have good managers!). Outside of management, mentoring, morale, and architecting (which are important), someone's individual contribution is usually an upper-bound on their effect on team productivity. For some individuals, this is very far from a tight upper bound. Drama llamas, prima donas, and assholes create dysfunctional teams, and poor communication will in general increase the amount of work that needs to be done due to people working with incomplete information and needing to re-write things more often. Argumentative perfectionists will get caught up in arguing the design goals, and changing requirements will result in a lot of lost work for the whole team. Egotistical programmers are more prone to large re-writes of other people's code rather than small additions, which dumps a large portion of their contribution into changing style with little or no functional gain. There are plenty of ways where someone with a large individual contribution may have a small, or negative, increase to your team's productivity. This doesn't mean you should hire the nice guy who can't code, though. Hiring decisions are possibly the most important decision you can make. Take your time to find the right person.