He was a typical computer weenie. He did not understand that when it became clear that McNamara was winning the game he was capable of playing, they changed the game. McNamara one "his" game, which unfortunately was not enough, and he lost the war, only it took Nixon and Kissinger another 5 years to figure that out.
A cold clear-minded strategic assessment would have shown that we could not win the war fighting the war that the politicians were willing to fight in the manner they were willing to fight it. It is an old old lesson.
Dereliction of Duty, by H.R. McMaster.
A great read. If you can bear it...