I think Imran had as much tactical mastery as any good skipper. His results were also as good as they could be in the Windies dominated era. His man management skills were too autocratic and tailored to suit the pakistan players of that era.
Since that style is not right for all combos, and because his results and tactical skills are not anyway significantly superior to his peers, I don't think he was a great skipper. Merely a good one.