We're talking foreign conflict here, this isn't football. It was Mac's job to make sense of strategy worked out by others and then deploy recourses as needed. When it became clear to all that he wasn't up to it he was replaced by someone that could and was willing to do what he was told.
The worst part was that Mac deliberately disobeyed orders; he was lucky he wasn't shot.
No we are talking about the incompetent conflicting policies coming from an administration that was totally clueless about it goals in Korea. An administration that only a year before the war that had withdrawn all US forces from S. Korea and announced to the world that Korea was outside “its’ area of influence”. Truman practically invited the invasion.