Hackman performance here frankly is the performance that makes it easy to criticize performances that do nothing that almsot seem to use the excuse that there role is too small to do anything substantial with it. Hackman takes what he has with Buck and makes more than anyone possibly could have in the role. From his first scene Hackman is able to establish a unique and effective characterization of Buck as a usually somewhat easy going fellow who certainly has a history that has not made him bitter. Hackman with a subtle accent and mannerisms he makes Buck a true man of the period.
Hackman is terrific with the absolute in which he establishes the various relationships he has with the gang, and he is really instrumental in making the whole dynamic of the gang work. With Warren Beatty they both manage to make they create a genuine brotherly dynamic with the way they interact and talk with one another. Also very importantly Hackman makes the fact that Buck is married to usually hysterical Blanche (Estelle Parsons) entirely believable. Although no one else he shows that Buck most certainly does see something in here, and does honestly love her despite her behavior. There is a quiet chemistry between the two that is just right for their unique relationship.
One of the biggest challenges in the role was really the idea that Buck played by a lesser actor could have been completely forgotten in the whole of the gang. Hackman makes himself standout without being an overwhelming presence. He finds just the right ways to stay noticed. Hackman makes Buck one of the warmer members of the group, who seems to always find the lighter sides of things making his same old joke over and over again. Hackman always stays absolutely realistic within in the group,a and his whole performance only ever succeeds in adding to the film.
The most substantial parts of his performance come though in his key scenes, that although they really do not focus on Buck Hackman bring the attention to himself nonetheless. The first being his whole first scene where he must fight with the gang as he jumps into action, and later when they are running away. Hackman is amazing as he shows how his thoughts are going a mile a minute as well as showing that Buck clearly realizes that there is no going back after what he has done. His other big challenge comes in his final scene where Buck is dying, Hackman absolutely succeeds in making Buck death really hit even harder, because of just how naturally he portrays the whole event. Hackman gives a very strong supporting performance that is the perfect example how an actor can really make the most out of just about any role.