I agree that McNamara got things wrong. That is not my problem with him. Everybody gets things wrong, comes with the territory. Failure to adapt, definitely his problem. But even that is something I don't hold against him. The guy was rigid, but most number guys are. If the math doesn't work, they have problems seeing other alternatives. He was an "X number of bombs dropped will get Y results and if we kill this many NVA/VC, we will win the battle" type of thinker. Again, not unusual, in the world and that I don't hold against him.
What bothers me is the guy pretty much ran the show for years, and then, in the late 60s, comes out and says the war can't be won and we probably should've never gone there in the first place. Where the hell was this thought in '62?
I'm not a big fan of Westmoreland either, but he never shied away from responsibility for the war. He owned it, knew it and died knowing it. He didn't always give the most accurate answers and was another bright bulb that lost it in the real world.
But McNamara tried to dodge the bullet when it was over. That has always bothered me.