TOFO's point is a good one in my opinion,
however you care to look at it Mc Namara was pretty near the top (LBJ) and you can take it one of two ways - McN counselled against the war and was ignored (at which he should have resigned) or he continued to support the accountants' approach to war that LBJ seemed to favour.
That LBJ should take the lion's share of the blame is, I think, reasonable - the US point of view of warfare was skewed from the top down - but McN is still far from being a poster boy for the "beancounters should be in charge" argument.
TOFO's final point is spot on - the political leadership should appoint the best fighting general they can in wartime, then stand back and let them get on with it, unless extreme circumstances arise. (I'm thinking of McArthur's idea to nuke the Chinese here).
Dave