Robert Duvall did not receive an Oscar nomination for portraying Frank Hackett in Network.
Duvall is terrific in being the Hatchet man in every scene. He walks into every one of the early scenes of the film with so little regard for anyone, and matches the intent of the character who intends to walk over everyone in order to meet his demands. Duvall accentuates the ruthlessness of Hackett incredibly well as he he brings such a particular bluntness to everything that he says, and there is not a delivery of his that does not have at least a tinge of viciousness of it. Duvall conveys as well the particular strategy of Hackett as he goes about attempting to take over the Network's news division from the more noble Max Schumacher (William Holden). Duvall in their initial confrontation Duvall presents Hackett as going forward with an unshakable command in himself as he basically states his intentions without any hesitations, basically sing everything will go as he expects it to while carrying just this general menace about himself that suggests a threat before Hackett has even made any. When Schumacher attempts to stop Hackett's takeover, Duvall is outstanding in unleashing the unholy fury of anger in Hackett as he goes about silencing the man through such smug assurance of his own position.
As good as he is as being the straight forward unrelenting hatchet man he should, what I really like about Duvall's performance is that he actually shows a different type of character or man from, Howard Beale (Peter Finch), who's lost in his own insanity, Diana Christensen (Faye Dunaway) who's also insane in the way her whole life is ruled by her uncontrollable desire to conquer the world of television, to even the head of the insane head of the corporation Arthur Jensen (Beatty) whose lost in his philosophy of a corporation to rule the whole world. What I like about Duvall's work is he does not present Hackett as insane, at least not in the way the other people are, although one likely would still have to be a bit insane to devise to kill a man just because he has bad ratings. Duvall though does not portray Hackett as any sort of fanatic, which can be seen in the portrayals by Beale, Jensen, and Christensen. Duvall's good in infusing a more realistic bent for Hackett as he's only really motivated by money, and the power of a potential power. He has no actual beliefs, and Duvall portrays Hackett's ambition as far more to the point. This leads to rather effective scenes near the end of the film when threats to his success come in the form of an ever changing Beale. Duvall's very good by giving a humanity to Hackett, by showing just how genuinely worried and troubled he is by seeing his position threatened. Duvall does not present any presumptions in Hackett, his mind is always in the present, and when he decides on the final death Duvall shows Hackett just as swift to the judgment as Diana, but there is just something far more honest in the way he comes to the point. Duvall shows that Hackett feels that he has to, but Dunaway keeps it within Diana's out of reality tunnel vision (this is not a criticism of Dunaway's work in anyway by the way). Duvall gives a very strong performance here. His role actually is a bit thankless. He has a bit less screen time, and in a way his character is kinda inserted around the other who tend to get the "bigger" moment in any given scene. Duvall though still ensures an impact by making the most of what he does have, fulfilling his role as the representation of corporate heartlessness as well as offering an interesting dynamic by effectively realizing the exact nature of this heartlessness.