The article alluded to the point of diminishing IQ return varying depending on the industry - I think it would be interesting to also measure the IQ of the team behind that leader - I wouldn't be surprised to find the tipping point to be some multiplier of the median IQ of the team in question.
The underlying work, published in Journal of Applied Psychology, was explicitly meant to the test the idea that the tipping point is a multiplier of the team's IQ. From the abstract:
"Following Simonton's (1985) theory, we tested a specific model, indicating that the optimal IQ for perceived leadership will appear at about 1.2 standard deviations above the mean IQ of the group membership."
The researchers' findings are consistent with this theory in the group examined ("midlevel leaders", which I think means middle management); they say future work will test the theory with other groups who have different median IQs.
