I believe Rumsfeld cares about the lives connected with the U.S. military. I believe his efforts are toward maximum economy in those lives. I don't think McNamara ever cared about anytning or anyone except McNamara. I think he revelled in press accolades of him as an intellectual, which is fascinating since there is little evidence that, after he joined the Kennedy administration, he ever did one smart thing.
With this in mind, any other comparison is irrelevant.