Well, to make it concrete then: I've seen teams get happier and more productive when some asshole is removed from the team; I've likewise seen teams get less pr

Well, to make it concrete then: I've seen teams get happier and more productive when some asshole is removed from the team; I've likewise seen teams get less productive because someone is added who drains morale, interest and productivity because they're continually negative and waste everyone's time with distracting concerns and a lot of "yes, but what about this?" type navel-gazing. I've found my own productivity fluctuating with different coworkers based on how well I communicate with them (where someone I struggle to interact with well gets along well with others). So no, you can't view overall productivity as the sum of individual productivity because there are factors like this that are a function of group composition. And there's a lot of factors that are not functions of individual productivity.